Rent vs Purchase Used (selling after trip): 4-6 month trip

Even with a long term rental discounts, I believe you will find buying & reselling is less expensive. On the other hand, the hassles of purchasing a used RV, maintaining it, and selling it when done are not insignificant.

The last time I rented was a 31' Fiesta Class A for two weeks - Rental - $2093.61. While you might get a better deal with a 6 month rental, it is still going to be large portion of the purchase price.