Curious what was/is your TW? With 3000 lbs max GVWR on the trailer, I wonder if it's possible to keep TW under 350. Based on layout, I would think it's possible.
Even if so, I would be concerned about frontal area, with a Class 2 vehicle. That's probably a major contributor to your issues (that, and the Rockies!)
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller