I've pulled my 26BH with a 4.7 Ram, then a 2500 Ram/Cummins, and for the last two years, with a 2011 Ram 5.7 HEMI. The 4.7 was underpowered for my tastes, the Cummins was awesome, but much more truck and maintenance than I needed/wanted. The HEMI is perfect for my needs.
It's pulled my TT all over the US in all kinds of terrain and did a great job everywhere. The RPMs run higher than average going over mountain passes, but I think my HEMI enjoys pushing it at times. It's good to work an engine and not baby it all the time, IMHO.
Good luck making your choice, OP. I do see the logic of buying a larger truck now, since you do have a growing family and may decide to upgrade to a larger TT in the future, even if you don't think you will now. And with a family, safety is paramount, and a 2500 would be a much safer drive than any 1/2 ton would be.
2011 Dodge Ram 1500 HEMI Quad Cab
2011 Jay Flight 26BH