I tow a Patriot camper on 37s and stock gears and still average ~19 mpg. I recently towed a fully loaded 6x12 uhaul and slightly felt it’s weight when passing or going up inclines, but never felt underpowered.
My wife and I were out in Maui the week prior. We toured the island and checked out Lahaina and did some kayaking and snorkeling just off of the Kamehameha Iki Park. Just devastating and our prayers are with them.
Recommend double checking the length of the lower control arms, one may be longer/shorter than the other. I had a similar problem and discovered my passenger lower control arm was shorter than driver. Just a thought.
Recommend checking the upper rear sway bar mounts to ensure the are broken and if not, torque them to spec. A little silicone spray on the joints goes a long way. I usually squirt some of the upper rear spring perches as well after power washing my rig.
I’ve tackled a bunch of blacks at Rausch Creek that folks “wanted to watch” and then were amazed the JT does so well. I was able to take lines that they struggled with. You’ll do great, especially since you know the trail.