Just a quick thought might be something like dirty girl gaiters. If I remember correctly they cover the top part of the laces and so would at least keep the laces from catching on your other boot. I think they are more designed to be used with trail runners than boots, so there might be less material/bulkiness to rub against your other boot, although I can't guarantee it. If someone has more experience with dirty girl gaiters maybe they can clarify whether this would be a good solution.