ive heard both that you should keep your stacks coverd while it rains and that rain will not hurt getting in there, even heavy rain... i work offshore and am gone 3 weeks at time. so i do keep em covered when i go to work but its a pain in the ass having to put covers on em everytime it rains...lemme know what yall think...
This may be a totally stupid suggestion... but can you just drill a small hole at the low point of the pipe under the truck to let the water drain out?