Towing with Chevy Avalanche will it be safe?

I don't know much about suspension, but quick research shows adding coil-over shock absorbers could increase payload quite a bit. Is this correct?

edit- seems there may not be any on the market for this year Av, will have to check further

per http://www.ehow.com/how_5099020_increase-payload-capacity-truck.html

I'd still be within GCWR of course.

thanks everyone for helping out.