Tough call.... for the load you have I think I'd stick with it - unless you just have a few grand burning a hole in your pocket
I'm worse on each end and am surviving - 3.73s with an 11,000K 5th wheel. I've thought A LOT about jumping to the 4.56s but just haven't done it yet. I don't tow all that much and when I do the truck does good not great. It really would be a frivolous/optional thing if I did it. At your weight and considering you have the favorable 4.10s I'd probably just run with it.
Before my current 5th wheel I had a TT of the same weight you have and it pulled with ease in all conditions. I'm out west with plenty of mountains and elevation too.
As you may or may not have read here there's lots of complaining about gear spacing and shifting of the 66rfe paired with the 6.4 Hemi. Getting to know the truck and manually shifting when towing will serve you much better than a gear swap. In a nutshell, the tranny in this truck sucks but IMO about 80% of annoying characteristics go away if you just think for it.