i looked at that when I still had my Tundra. You are right in thinking that it needs to be tweaked. With the extra weight in the back, the truck won't send enough braking power to the rear brakes to take full advantage of it if you level it. HOW much to adjust it is the bigger question. If it was me, I'd find some abandoned roadway and do a few emergency braking tests. Of course, you do all this at your own risk!
With your truck/camper loaded up as you intend to use it:
- Test your stopping distance from 60 MPH
- Pull the ABS fuse
- Do a test from a slow speed if you need to get used to how the truck may feel without the ABS... it could fishtail rather nastily if setup wrong
- Once you have the feel for non-ABS braking, do a few test from about 30 MPH and see which tires lock up first, front or rear. Will likely be just one tire, likely in the back since it was setup for unloaded braking before
- Adjust the brake force prop valve
- Retest
- Repeat until the fronts lock up first
- Back off the adjustment and retest until in appears random which locks up first, back or front
- Plug the ABS fuse back in
- Re run the 60 mph test.
If our hunch is right, the stopping distance will have improved.
DANGER!!! If you take your camper off, the valve will need to be readjusted... with all that extra braking force going to the rear tires, without a load the overall effect will be vastly longer braking distances when unloaded!!!!!