I think an RV would be too expensive for you. I doubt a private owner would want to rent to a 26 year old male (the highest risk for problems) from out of country who might put alot of miles on the vehicle. Nothing personal, just actuarial. Also, fuel could eat up half of your budget.

I think your best bet would be to rent a van (I have not researched this). Perhaps find an Ace rent-a-car and rent a van for 2 months. You could sleep in the back and have plenty of room for photo gear.

You might want to fly into Florida because rentals tend to be cheaper there. I did a quick search for a full size passenger van (ask for the extra seats to be removed) for 61 days this Oct-Nov and the price was about $3300. Use a Mastercard/Visa Gold card or American Express card which will cover the insurance. But be careful of time limits on the insurance because the credit card companies sometimes have 30-60 day time limits for rental insurance.

If you are more adventurous (you are a 26 year old photography student, right?) then buy a cheap car on Ebay and then sell it/scrap it/donate it when you go home.