2500 is fine but need to supplement the coil springs with probably any 5ver no different gas to diesel.
7000-7200lbs is your real world rawr based on the weakest component. Rims/tires. Again, no different gas to diesel. Regardless of the 10k gvw your 2500 is sporting. Axle itself is good for 10klbs.
Hemi = half the torque or less of a comparable Cummins. Hemi will pull a 12k 5ver. 65rfe is a reliable transmission with poor gear splits for heavy towing. 4.10s make it more acceptable but still noticeable. Not that the 68rfe behind a 2500 diesel is anything to write home about. But the diesel has the torque to mask some of it.
12k 5ver+ Hemi = Right lane and loosing speed up grades with a 12klb house behind it.
Diesel = Let er rip
How good are you at driving slowly?
And where are you towing?