I worked for a wireless ISP that had this problem with one style of dish we were using and this was the solution the engineers wanted us to take (just stripping the insulation to let water drip out before it got inside anything).

It was dumb because the POE the line was going into would very easily catch fire if water was introduced through the Ethernet cable. We had alternative dishes that we should have been swapping out for, but of course they wanted to save money instead of being safe.