Yes, he sure does need to have a chance to let his hooves dry out. Gosh I can't believe you are still wallowing in mud - I mean I believe YOU, it's just unbelievable. I might be considering moving the horses, if possible, if you can't get this cleared up. Unless your horse can have some time on dry ground or a dry stall, you are really fighting an uphill battle.
Is the horse hitting toe first or flat-footed when it walks at liberty on flat ground, or hitting heel first?
If it's hitting heel first, it isn't that sore but still needs attention.
Flat-footed is ok but not great. Toe first means those frogs are really sore and need extra care.
To treat the hoof on the days you can get to the barn:
1. Be sure to always soak the frog out good. I use a very dark mixture of betadine and "baby butt warm" water. It would be ok to put a capful of clorox in the mix but no more than a capful. Too much clorox is invasive to healthy skin plus, if the horse is really sore, even that little capful in a gallon of water could be too much.
1. You could buy a soaker like White Lightening or Clean Trax<--sp??
That isn't something you would do every day, just follow the instructions on the box.
2. ToMorrow, the cow mastitis treatment, is some of the best stuff I have ever used and can be applied twice daily, if need be.
Since you can't be there every day, I would recommend pouring Absorbine Hooflex "Thrush Remedy" on, around, and in the cracks (including the sulci). It is absolutely non-invasive to healthy tissue and will stay in the hoof for several days. I use it as a preventative, once a week. Hooflex® Thrush Remedy – Hoof Care – Products – Absorbine
Tractor Supply carries it and a couple of the local feed stores also carry it.
The ToMorrow is generally found at the Co-op but, if you don't have a co-op feed store, your TSC may carry it.
Be diligent about treating the hooves on the days you can get to the barn and be patient.
I agree that, if you see flaps of frog, to very gently snip them off without cutting into the healthy frog.
Diet can also make a huge difference, believe it or not - what's he eating?
Hope this helps:)