pretty rad dude! pretty much exactly the same as the one I built a year and a half ago..which is still rocking on the the roof top..
https://independentoffroading.com/index.php?threads/radio-information-guide.335/page-3#post-53514
question for you though, would you happen to have a SWR...
how, unless you have too much line. Should be enough to hug the truss and held in place with mini zippyties. and the seals, shouldnt be an issue unless you have uneven/scored surface. or could be the line where adjoins the disc/spacer thingy isn't sealed properly, you know what I'm referring to...