Can anyone give me any advice please about re-waterproofing lightweight tents? I've never done this before and our tents are all needing done this year as when we took them out in May 1 leaked. What I'm wondering is: 1 what's the best product to use? 2 does it need to be done outside or can I do it indoors (thinking our hall as it won't be used over the summer and can do more than one at a time)? I'm an experienced xer but feel like such a rookie when it comes to this!