There isn't a reason to have a diesel unless you plan to tow something heavy some of the time or need the extra range. Gasoline engines haul TCs just fine.
However, I think you should consider a DRW. For short bed, I think that means Ram. I don't think anyone else still makes a short bed. You could put something in front of the bed on a long bed. Some people do that. Personally, I think it looks strange.
I have a double slide 9 1/2 Host. I hauled it on a 11,400 SRW for 8 1/2 years. I did upgrade to 19.5 G tires to give more tire capacity. My DRW hauls it better as expected. I got by with the SRW because I had to. I just carried less water, kept the grey/black tanks empty, and only carried the minimum. Besides the weight capacity, the DRW will have noticeably better brakes.
Even with the DRW, I've pushed my 14500 GVWR fully loaded. On trip, I towed my wife's Uncle/Aunts TT behind on a trip to Yellowstone from the Seattle Area and back. It had no issues even over the Cascades with the diesel.
In any case, you can do it with a SRW, but you have to accept some tradeoffs.