I see AF811s being hauled around by SRW trucks all the time, most are the short bed model 811, which is built about 4 to 1 compared to the 811 long bed.
Knowing what I knew in 2009, and what GM trucks were rated for at that time (fall 2009), I wouldn't want to haul any AF on a 3/4 ton GM truck.
The weight ratings increased in 2011 on the GM trucks when the chassis was redesigned.
I understand your desire to stick with an SRW truck - they are much easier to deal with as a daily driver, particularly in traffic and city driving.