How to decide pre owned RV for full time 50’s amateurs??

All you wanted to know
https://www.rv-dreams.com/

Do you have a truck to pull a trailer? If so, rent a trailer. If not, rent a Class C as that is the most common. Get out and RV in something and decide what you like. Need to do some off-grid camping and some RV-park camping and see what mix you like. These answers will make more sense after going out once. And buy used for your first RV.... you may change your mind in a few years.

There's no substitute for going to RV lots and shows, to get inside the different types and brands of RVs.
Many see Class B's as too small.
Many see Class A's as too big.
No one can answer your question until you get acquainted with the different types of RVs, to narrow down the choices.

Rent the different types to determine which suits you and your camping style...RV parks or dry camping.

“We are not rich (about $100k banked” and in your 50s? IMO a HUGE financial mistake. About the biggest one you can make too. Health care insurance alone will eat that 100k and more until you are 65 and eligible for Medicare.

We burn through about $5k a month in vacation mode. That is staying at some private and some public parks for 3-4 days at a time and traveling about 250 miles to the next one. Towing a car behind the motor home helps. Socalled security covers about $3600 of that, the rest comes from the nut. When I'm not in vacation mode I work 2 part time jobs and take less from the nut.

But you won't be in vacation mode. You'll be working. Escapees and FMCA has a network for workcampers which is what you'll be doing. You normally get a free campsite for the season and maybe a stipend. The more connected you are to the workcamper world, the better the gigs. You'll be moving lock, stock and barrel every six months.

So, basically, you'll be trading one rat race for another. The only difference is your office as a workcamper has a better view.

Wait a while, judiciously tuck away every cent you can and hit the road when you can afford it. You'll enjoy it so much more. Work while you can, because eventually you won't be able to work at all.

500 a month? Not nearly enough for food, fuel, camping fees, insurance. Even if you were to camp host 12 months a year your going to need around 2000 a month. What type of RV? Until you go shopping and look how are you going to know. Even a moderately priced package could set yoi back a 100K.

We have been self employed (and paid for our own insurance) for the last 20 years.

Have you priced health insurance? We just turned 65 but we were paying over $20,000 per year with a high deductible.

If I could be blunt, you can’t afford it. Next time the economy takes a dump (and it will), pick up work will be hard to find.

Save up a lot more. Maybe try living in a used travel trailer or rent a park model in an RV park to expose yourself to other people full timing, while keeping your jobs.

Maybe take classes and find careers that pay decent and let you move around.

Itinerant nursing comes to mind. I have talked to several. They work in Maine or the like for the summer. Take a month or so off then work south in the winter.

Another guy was a Marine diesel guy and followed the boats up and down the Intracoastal year round in a nice fifth wheel.

Pipeline work.

Good luck.

You'll probably get 3,000,000 different responses !!!

Each has their strong points and their weaknesses. Personally, I like a TT as
we unhook, setup and then use the TV to go touring/sight-seeing.

5th wheelers seem to be the closest to a real house but are large to tow/maneuver.

I'll let other chime in regarding class A/B/C - I've never owned one.

You're taking the right steps, asking questions before you make a commitment.
Continue to ask lots of questions. Go to RV shows and dealer lots. look at every type and decide how you will use the RV. Will you change locations often or stay in one place for long periods?
There is a lot to learn but, it's not difficult. Take your time and don't be in a hurry to buy.
As mentioned, consider renting to see if you really like the RV life.

No one can give hard fact advice...opinions yes:

My opinion. Before you chuck it all and sell everything and burn bridges, rent an RV (maybe check out Cruise America) and hit the road for a month. Stay strictly within the budget you outlined in your post.....see if you can make it work or even it you like it....

There are rewards to RVing and there are challenges.
Good luck with it.