Can (or maybe they already do?) the horse come in for some time outside of the mud?
I am working on getting my horse out of boots and truly barefoot but have issues if she is out in a wet and/ or muddy paddock all the time. She comes in for a few hours everyday to stand in a clean/ dry stall. This has helped her feet from getting too soft and thinning (exfoliating) the soles prematurely.
As far as boots, the Cavallos are the best I have found. The scoots didn’t stand a CHANCE in the mud (lost and SO hard to find even with neon straps) and the easy care line doesn’t fit my horse properly. I have 2 sets of the Cavallos so one can be rinsed off (I feel they last longer if I don’t use a brush or soap, just warm water and hands) and drying while she wears the other then swap. She still gets boots for frozen ground as she is very early in transitioning out ( and has a complex history).