I lived full time in my 1997 Ford based class A Bounder, that is 30 feet long. It has a 100 gallon fresh water tank, and a 400 watt solar system. In addition, the class A typically will have a built in generator, while a class C or B do not have the excess cargo rating, thus no generators is typical.
If I where planning on living in the RV, first I would want a RV with fuel injection, not a carburetor. Carbs can evaporate the fuel over time it is parked, and thus require a rebuild if not started on a regular basis. I think that my buddy has a 87 class C, it came with a carb. Fuel mileage is also better with fuel injection, so is power, and it is much easier to pass emissions testing, should you live in a area with testing.
1985 is over 30 years old. Check the roof out well. Check out the brake fluid, with a paper towel in hand, dip your finger into the brake fluid. It should be clear looking. Clean your hands soon, the brake fluid is acidic. You might need to change the brake fluid - it should have been done every 4-5 years, but probably has not been changed in a long time.
Check the transmission fluid. It should be a light red color. If dark red, it will need to be changed soon. A transmission rebuild for the 85 van would cost $4,000 - give or take $1000.
Check the radiator (before starting it). The color should be green. Not rusty.
Think about how you are going to live in this RV. Will you be able to take a daily shower? How many days will the 20 gallon fresh water tank last? Or is it a 10 gallon tank? E-250 only has a 8,800 pound GVWR, the curb weight of a camper van is probably 8,000 pounds, leaving you just 800 pounds or so for your weight, and pets, clothes, camping gear, food and water. They do not put 25 gallon fresh water tank in on purpose, they can not handle the weight.
My advice? That camper is to small to consider living in it. Select a class C, and you will be able to take showers for at least 3-4 days between needing to empty the grey water tank, and refill the 30 gallon fresh water tank. It will have dual rear wheels, a 12,000 - 14,000 GVWR, so can carry about 1,000 pounds of stuff in addition to the 30 gallons of fresh water (240 pounds). You will have storage above the cab, so you can get things out of your way by placing them up there for a while.
Better yet, what I have is a Bounder 30E. They made the same floorplan in Pace Arrow, Southwind Stormy, and other brands. It has a rear queen bed, 100 gallon fresh water tank, no slide outs, fairly light compared to the 17,000 GVWR, so I can carry 2,734 pounds of stuff. With the 100 gallon fresh water tank full (800 pounds) and full fuel, I checked the weight while on vacation once, it was right around 16,800 pounds.
The 100 gallon fresh water tank, I could take daily showers for 2 weeks before going to a full hookup campground to dump and use the laundrymat at the campground. This saved on camping fees. I could camp all over the west for free at BLM campgrounds, or National Forests where dry camping is very low costs.
30 feet long is not unreasonable length, short enough to get into most campgrounds, and light enough to go down the road and climb the mountains at a reasonable speed, with decent fuel mileage.
Don't worry so much about MPG unless you plan on driving it coast to coast every year. If you only put on 5,000 miles a year, the MPG does not really matter. If you put on 2,000 miles a year, that would be 200 gallons of gas at 10 MPG with the E-250 van, or 300 gallons of gas in a larger class A getting around 7 MPG. That extra 100 gallons of gas every year is only going to cost you about $300. But you will be able to spend much more time in one location in a larger RV, because you can shower daily inside it, not needing to spend nearly as much on campground fees.
Also for your RV insurance. Call the agent once it is parked. Tell them to suspend the liability coverage until you need to drive it again. If this will be 3+ months, then the cost to insure it for a year will drop a lot.
Will you have an additional car? If so, you will automatically have coverage for the first 10 days that you buy an additional vehicle, so you can buy it, drive it to the place you plan on parking it, and not have to buy coverage right away. Get the smog certificate, and registration in your name right away. Once parked, suspend the liability insurance. Or if you don't want to drive it to the location it will be parked, have the seller drive it there, they should have insurance on the vehicle anyway.
One advantage to buying a travel trailer is you don't need to purchase insurance for it, or it will be much cheaper insurance. You can rent a U-haul truck (one of the larger moving vans with a hitch on it) if you need to move the trailer around town. It will cost $40 a day and mileage, and gas, but much less expensive than buying a truck to move it around.
Solar panels will make the whole thing a lot easier to dry camp, and to camp in forests, without the need for a generator.
SunElec.com is a great place to find a couple of 100 - 150 watt solar panels. Figure that you will need about 240 - 300 watts to run the RV without needing to scrimp on power. You can still run a laptop, via a 12 volt 100 - 150 watt inverter. It will take 12 volts and make it into 120 volts. You can run a ink jet printer with a MSW inverter, but not a laser printer. It will take a much more expensive Pure Sine Wave Inverter to run a laser printer.
Good luck with your purchase!
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a
Porsche or Country Coach!
If there's a WILL, I want to be in it!
I havn't been everywhere, but it's on my list.
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