I have a 2018 Grand Design Reflection 303RLS. 33ft long, GVWR is 12k. Opposing slides in the rear living area - tons of storage. I started out pulling it with a 2017 Ram 2500 with the 6.4 hemi. It did a very good job, had plenty of payload in Bighorn trim. Coils in the rear - no squatting when hooked up.
Payload varies by vehicle - you might get estimated numbers, but best to look at the load sticker in the actual vehicles driver door jamb.
So if you want the gas engine, I don't see any issues going with a 2500. But shop the 3500's at the same time - you may be surprised. Since you want the short bed, you need to be concerned with the possibility of the camper contacting the cab. So think about the Anderson hitch or a slider. Be aware that the auto sliders can't hook up at an angle.
And if you don't want 4x4, you might have to order. Good luck
