[gearhead]

All I can add is you may be able to upgrade the Avalanche a little bit. We had one that was maybe a 2007 or 08. They made some with, I think the 6.0, and I may be dreaming it, but I think they made a 2500 version, but not for long. We had the usual 5.3 with a 3.42 rear axle ratio. Anyway, I had Sour Lake Motors add a factory transmission cooler. The fittings are all there, they just order a kit from GM and installed it just like factory. So if you really want one that doesn't have the cooler you can add it.
But I agree with John, you might be pushing the limits of a half ton. Now if you knew for sure you would only be towing around SE Texas, south LA, etc. and the numbers are all marginal, you "could" be OK. But I would be looking at a crewcab 2500. Good luck with a used truck, looks like all the area used car lots are picked over after the storm.