Go with a 350 SRW. I started with a 250 and just upgraded to a 350 last weekend so we can get a 5th wheel. Trailer weight alone, you'll be fine with a 250, but the pin weight will be your limiting factor. My '15 250 had a cargo capacity of 2204 lbs, my 350 has 3477. I have a list of 12 5th wheel toy haulers in the 36'-39' range and there were 2 that I would have considered towing with a 250, and both would have been overweight, even with the pin weight only being 2400-2600 lbs. With the 350, I can legally tow every one on the list. My short list ranges from 2600-3000 pin weight, most in the 2600-2900 lb range.