[rjdhomes]

pjcnlv, I agree that you will be better off with the Columbia. One more reason would be the cab cut-out in the M2 is so low that it is uncomfortable except for a smaller and more nimble person than myself.
You will more than make up the price difference if you ever want to sell it or trade up. The M2 will not have a problem with towing capacity, but you won't be happy in the mountains or a 40mph headwind.
Without the extra height in the Columbia, it will be suitable for younger kids but not adults or bigger teens.
If you do use the basement air, remember that KVH now makes a low profile in-motion satellite dish, I think it adds 5".
I just ordered an M2 crew cab with the 330HP CAT and the Eaton Ultrashift, it was ordered with a PAC-Brake exhaust brake. I am not sure who makes the brake but I will research it. The M2 is also available with the Mercedes 300HP and the Allison.
A 10kW generator is enough to run 3- 13,500 btu roof air conditioners, check it out but I think that the basement air will be a single unit and be ok with the 10kW.

Good Luck!
Bob