The snow should not be building that kind of a ball in just a few minutes. We trail ride for a couple of hours at a time (some shod, some not) and do not have that kind of issue. The ice balls form more from the heat melting the snow while they are standing around.
A couple of good smacks with a rubber mallet will break up the ice ball. Much better than spraying un natural products.
I've never had this problem before when working him but for some reason the other day I had to keep stopping him to clear out the snow. Normally I don't worry about his feet as they clear themselves pretty well and he's just been trimmed, last night I went to pick them once he was brought in and with the exception of a little collected snow round the edge his feet were pretty clear. I have no idea why it was building up so badly a few days ago.