I briefly skimmed the treads so I apologize if this has already been mentioned.
Depending on the style of breaks you have on your unit you may want to check the owners manual for proper adjustments of the physical brake itself.
It's been last year since I've read the owners manual for the trailer brakes on my '13 Jayco, I don't remember the exact stats. It mentions the brakes require ####km or ## of medium pressure stops to properly seat the brakes. Once you've reach the requirements there is a procedure listed for how to properly adjust the brakes by jacking up the trailer and using a brake tool.
When I first hooked my truck up to my trailer I was in the same boat, 10 wasn't high enough. After I adjusted the breaks as per the manufacturer I was able to knock it down to 6.5-7 is depending. I think it may also depend on the temperature of the breaks when doing the test?
There are quite a few videos on YouTube for adjusting breaks... Here's one.