I’m in the camp of all horses have “thrush”. Just like folks have bacteria on their skin and yeast in places. It’s only a problem when it’s “too much”.
For a horse that you can’t physically handle yourself every day I think it’s tricky. If horse has any significant thrush it’s certainly not helping his other heel issues. But “curing” the thrush is unlikely to “cure” his heels.
If you see your horse once a week, I’d suggest trying a strong thrush treatment followed by packing it with cotton bits once a week and adding a cu:zn supp. I dunno that paying for daily thrush treatments done by barn staff will have enough reward to be worth the cost. Depends on how much barn will charge. There’s about eleventy billion thrush treatments. Desitin based concoctions and Vetericyn hoof spray are my current favs.
IME hoof boots increase thrush more than pads w pour in under them.
IME Magic Cushion provides comfort and discourages thrush. But I’ve only ever used it on one horse and he was shod.