Be sure to arrange for medical insurance and budget around $1,000 a month for the two of you until you are hopefully employed where the company provides medical insurance. That is the downside to the good old USA where everything is profit driven.
For an RV you will have the most space for your gear and clothing for temperatures that can vary widely in a Class C motorhome. Motorhomes devalue with age more than mileage so if I was looking to buy one it would be a 2000-2006 one that had less than 70,000 miles on the engine and transmission. I would budget for the possibility of needing new tires and having the servicing brought up to date as an RV that has sat and not been driven for a year or two should have its brake, motor oil, and automatic trans fluids changed and new filters and radiator hoses and heater hoses and radiator flushed. Batteries (motor and house) probably will need to be replaced if they are more than 4 years of age. This preventative work is easier to do before you start your travels and will greatly reduce the chance of a breakdown while in the middle of nowhere - and there are lots of those kinds of places in the USA.
I would buy from a private party and save 10-15 percent. A dealer is not going to have the maintenance records for the vehicle while a responsible private seller who took care of their RV is going to have these so you know what has been done and when or if it was not done.
With either type of sale I would have the dealer plug it in overnight and check the fridge, water pump, inverter, furnace, hot water heater, vent fans, toilet, etc. before you leave the seller. A new fridge can cost $800 to $1200 plus the labor to install it. If there are awnings open them and check their condition as a replacement can be very expensive and time consuming as these are items that need to be ordered.
If you plan to sell it after your trip I would do careful research to see which makes and models are in demand and will be easiest to sell later. A Class C Roadtrek for example takes a huge drop of 25% in value the first few years and then it levels off. More people are moving toward smaller and more fuel efficient and easier to maintain and drive motorhomes like the Class C and B ones.
In your place I would get a Class C and have it rigged for towing a small sedan. Much easier to get somewhere and park the RV in a campground and then use the car to do excursions. In many parks the available parking spaces for RV's can be very limiting.
If you plan to end up in the New York area then buying the RV in a place like Arizona where there are lots for sale and no rust damage from salted roads or salt air, and drive from from the western USA to the east coast you will cut your driving distance in half.
For my part I would want to start in either San Diego in California or in Washington state. Sales tax is a factor and there is no general sales tax on transactions in the state of Oregon. In Tuba City in Arizona by way of contrast the total sales tax rate is 13.725 percent.
For state and national parks and US Forest Service and BLM (Bureau of Land Management) campgrounds which are primarily in the western half of the country, their websites are excellent resources.
