Don't over think it. Just look at the sticker for GVWR and subtract about 8,000# (ball park # for a 1 ton). So a 11,500# GVWR will yield you 3,500# of capacity. A newer 14,000# GVWR will yield you 6,000# capacity. Stay under GWR should keep you under your axle ratings.
A 14,000# 5er has a pin weight around 2,800# (pin weight about 20% of gross)
A 10,000# TT hitch weight is around 15% of gross or 1,500#
These are all ball park numbers but should give you something to work from while shopping.
As for SRW vs DRW there are plenty of threads to debate that.