Lift kits?

Depends on how much lift and the type. A body lift would clear bigger tires but not mess with the suspension. A suspension lift depends too. Something like longer leaf shackles wouldn't change how the leaf carries a load although it might require longer bump stops. New springs obviously it would depend on the spring. Up front would likely involve new upper control arms and adjusting the torsion bars. I'm not really familiar with lifting GM trucks specifically so I'm just speaking in general terms. I do know they have leafs in the rear and a torsion sprung IFS. Another consideration is that lifted trucks generally don't play nice with fifth wheels.

Got a little long winded there but the short version is that you can tow with a lifted truck if you're careful about how you go about it and aren't planning on a fifth wheel.