3k rpms ain't bad. It's normal that you'll have to pull in 3rd or 4th gear with that big of trailer and that engine.
A bunch of bolt on stuff will help a little bit not much. Gearing down is a better bang for the buck but not worth it really. Just let er eat with the trailer hooked up.
Sounds like another HD diesel SUV customer IF one of the big 3 would actually make one! The only real diesel SUVs have been out of production for so long they're all wore out. I can't believe a mfg hasn't jumped on this yet. Factory Duraburb or Excursion Diesel would sell like hot cakes ...