I’ve been going back and forth on what to do as well. I’ve look a lot at Raylar’s products - they really know what they’re doing with the 8.1s. To get their super charger installed I was quoted ~$10k - $12k. Not sure it would be worth it for me...
I live in Colorado and the 8.1 has pulled in the mountains pretty well. Our previous TT was 35’ and around 9,000 lbs.
Have you talked to Duraburb? Then can put a Duramax in your Suburban. They won’t/can’t put one in my Burb because it’s too old. They only work on 2003 MY and up. If I had a 2003+ I’d seriously consider converting it to a Dmax.
I’m not convinced a Express 3500 6.0 would do well out west, could be wrong though. They de-tune the engines in the Express vs the pickups too.