You're going to have so much Pro and Con information, this alone will make you tear your hair out, start drinking or drink more
Regarding padding the hoof:
It was pure chance my horse ended up wearing Boa's w/partial pads for 8 months. It turned out to be the perfect thing for him and his living environment.
He was only kept in the stall at night, as is the usual routine here. I turned him in the 1/2 acre barn yard during the day.
As a sidebar, he was rotated 8 - 9 on the LF (measured from the dorsal wall) and 5 degrees on the RF. Myself and the vet were astounded he never once exhibited the typical founder stance, I am seeing with your horse. Even more astounding, he never once layed down when he was outside. He would crash in a big way in his stall every night but somehow made it thru the day without going down
Back to the boots. I had talked to Customer Service at Easycare (who was fantastic by the way) and she nixed the Rx boot for Joker's scenario.
The Rx boots are not meant to be left on more than a few hourse daily.
She said the Boa's could be left on him for up to 12 hours. So Joker went outside in the Boa's with partial pads every day. I took everything off when he came in his stall at night so his hooves could dry out and "rest".
The vet wanted mats in his stall with shavings on top. Thankfully I already had grid mats in there. The biggest thing was deep cleaning his stall every day because he drank a LOT of water and ate a lot of salt; I imagine from the fever within him.
The Boa's gave his entire soles the coverage they needed to protect them from the elements, like stones, rough edges of the ground where there were holes, etc. He walked a lot more fluid wearing those boots.
The part pads were cut specifically to protect from the tip of the frogs back to the heels, and to just inside the whiteline from side-to-side. Their purpose was to relieve pressure on the heels and keep part of the sole further protected.
The vet was adamant about NOT covering the toe callous with the pad.
It was amazing how the toe callous stayed calloused inside the boots.
Boa's may not fit your horse, you may need something else, if you go that route. But the key to successfully using a trail boot, is a secure fit AND the partial pads.
If you cut up the pad the treadmill is sitting on, a good pair of kitchen shears work well and so do pinking shears.
Put the smooth side of the mat to the sole of the hoof.
Your horse needs some cushioning, I think we all agree on that; it's going to come down to what works best for him and sadly you will have to just Go With The Flow as to what makes him comfortable and will aid in his rehab
Because you work, I really like the EquiCast idea, if it would make sense in your case.
Perish the thought I ever have to do this garbage again, I probably would stick with the Boa boots and partial pads because it's what I know and my only job these days is being a slave to anything that whinnies, barks, or meows
That was pretty much one of my famous "yes, I guess not" answers------