Thanks for the input guys.
I love the RTV silicone, even though it's a little hard to get a hold of. I did some digging and found out about it online some years ago... mostly from DIY rimless builds. I used it for my previous build, this 100Gal seahorse Cube:
It dries really quick, skins in 5 minutes, which makes the process a little stressful though.
Thanks for the offer Eli, but I'm sticking to my (silicone) guns
Besides, UPS is already en route with another 7 tubes & should get here by late next week. Gives me some time to catch up on the stand cladding and canopy design.