Not to be rude but the trouble with your first 2 paragraphs is this,
From what ECR033 has said it appears that this problem is intermittent( even if it isnt we still dont learn anything from this), so when testing the current draw with a multimeter if the short is not on at the time of testing, the reading he gets will tell him nothing, if the short is there it tells us only what we already know, but not where the problem lays. We already know at some time the current draw is enough to blow the fuse, the difficult part is what is the cause? It may be a case of disconnect one at a time, all the accessories that feed off that fuse and drive the car for a while, a process of ellimination, not great but it may lead to a solution.