What suspension upgrades i should consider for my truck?

Those dually's are heavy duty. There is a big difference between a SRW and DRW, even if they might have the same or close to the same ratings.

We had a GMC and did nothing to the suspension to load it with the biggest Lance and towed a 6000 pound boat. The suspension needed nothing.

I doubt if you will have to do anything, but a hitch extension, see Etrailer for that.