RV Full Time, First Time.

Look around at campgrounds in the area you are thinking of. Many campgrounds will have "seasonal" campers for sale that includes a lease agreement for long term staying at the campsite. These campers are already setup and ready to move into.

I second looking at a TT, or Travel Trailer. For your money, you could pick up a very nice TT, likely with more living area than a Class C. When you find a campground you like, the management there probably will know someone who can tow the camper to the campground, or the campground itself may run some sort of towing service.

Double and triple check with the campground management about monthly fees, electric rates, maintenance fees, etc. Also, some campgrounds may refuse you if you outright say you will be living there full time. Actually, local zoning laws may require them to not let you stay "full time". If you stay as a "seasonal", you may have to move out of the campground for a certain amount of time, sometimes just a couple weeks.

Good luck!

You will get a newer nicer and likely larger TT for $12k.

Otherwise, take your normal household budget and redo it with an RV instead of a house/apartment. If you are in an apartment, remember to add a maintenance budget item.

While you can live cheaply in an RV, if you live the same way you lived before, there won't be a lot of savings.

Many campgrounds have wifi though the quality varies greatly. You will want a site with water, electric and sewer (or you can get a portable tank to dump your sewer. Long term stays most parks charge you per KWH. Heat & cooking is generally propane. If you are in a colder area, you can burn a lot.

If you are a long term, keep in mind the power and propane consumption to keep warm or cool. Electricity (usually a separate bill for long term tenants) and propane can be quite expensive in an RV since neither the AC or heating systems are efficient and can gobble up much of your hard earned $$$. I agree a travel trailer would be the best way to go, the systems in a low cost motorhome will start failing without use. Fuel system (including tank & lines), cooling system, brake lines, brakes, bearings, exhaust system, are all things that can cause problems when left unused for long periods of time.

I second the TT idea. The worst thing for a motor vehicle is letting it just sit. It will certainly help the engine to be started and run for at least a 1/2 hour or so now and then but that doesn't roll all the bearings and sling oil in the drive axle. I've seen ring gears heavily rusted on the portions that are not laying in the gear lube. A vehicle needs to be driven.

If you are staying in one place you dont need a truck. If you do need to move to another park, getting a pick up to move a TT is cheap and easy. The worst that will happen to a TT from not moving is tire, wheel bearing and brake issues which are all low skill repairs. Most RV parks have poor wifi. The most expensive RV issues are Refrigerator, Air conditioner, furnace, water heater and water pump. The fig issue is expensive if you replace it with a propane model, if you replace it with a residential it would be about $300 to $400.

Whatever you decide on, DONT leave the black tank valve open all the time. Let the tank fill up before dumping. Use a generous amount of water when flushing the toilet. The black tank monitor is useless.

Be extremely careful when shopping for any RV as water damage is the number one issue. Any musty smells are just about a sure sign of water damage. Check the roof now and then for caulking issues. Seal around all the windows, marker lights etc and do routine checks. You cant be too careful about water. People will try to mask the damage. If you are unsure of your inspection abilities get help.

A slide will make the living area a whole lot nicer. They can have issues with water or mechanisms but you wont be running it in and out a lot.

Have you checked the area you want to be in for parks?
Some RV parks can/will refuse a rig over 10 years old. So find a place you might like first for their rules.
For 12K for the first Class C you will be looking at older used.
Any rig with tires over 6-7 years will need new tires if you plan to do any traveling. Forget how they look. They can look brand new and have only a couple hundred miles on them but they are still NO GOOD.
RV fridge in an older unit may be on the way out but if you plan to stay in one place it can be changed to a regular household fridge.
I think in our situation it is an unwise move but it is your move
your expenses will be;
Lot rent
Electric
propane .
maybe taxes
Will the park you are in allow propane to be delivered or will you have to drive the rig to get propane.

Can you fix the problems on the rig yourself or will you have to pay when the furnace fails etc
Lastly do you have enough knowledge to buy an older rig without getting taken and having a rig that is a disaster (there can be a lot of hidden damage) and no money for repairs. Lots of first time buyers get taken on older units. What would you do then?

Really evaluate your needs... A TT might serve you better than a class c

I also have another car, so I won't be driving my motorhome. I may start it up once in a while to clean out the pipes and keep it from aging too hard.

What's it like living full time? Is Wi-Fi out of the question? Electric bills? How do i get electricity? How do I get water? How stressfull is living full time?

Welcome to the forum.

IMHO, If you are going to stay in one place for years, I would suggest that you get a travel trailer. If necessary, have someone deliver it to the RV Park.

Propane (for cooking and heating). Groceries, of course. Repair/maintenance on the RV. (With your budget you will likely get an older RV, many of which will need some work.)
Insurance.
A way to get around. The motorhome is transportation, yes, but also your home. With a motorhome, every time you need to leave the campsite for something, you have to undo all the hookups, unlevel the camper (assuming you had to level it), and make sure your site will be available when you get back. Then level/hook it up all over again when you return. And motorhomes suck gas like you wouldn't believe. A class C big enough to live in will probably get about 9 mpg.