I've had great luck, as far as rain entry, with my hardshell RTT. If it's a torrential downpour with rain blowing sideways, then I might get some water at the bottom of the entry door. Then next day prop up the mattress a bit to dry it, which usually takes little time. It never gets soaked, just damp, and that's usually because I don't zip that door down, even in rain.
I've slept up in there during big rains with great success. I have identical zippered windows on each end and entry doors on each side. I've found that the slight overhang from the upper hardshell is sufficient, even in hard rains, to keep rain from coming in any of the four screen points (two windows, two entry openings, all screened).
The key for me with my style tent is to zip up the window coverings so there is just three-four inches open. The end windows have a covering on the inside of the screen that zips up from the bottom. The main entry, where I have the ladder, has a little awning over it with triangular side panels, and I don't zip any covering over it, even in big rain.
I plan on treating the rip-stop nylon RTT fabric with some
303 Fabric Guard Water & Stain Repellant
before winter.
All in all, through about 250 nights of use in the last 13 months, I've been quite happy with how my RTT has held up to extreme weather. I'm designing a quilted blanket liner to snap or hook&loop to the interior as wall insulation for cold weather camping.
A lot of what you do for water ingress, with an RTT or a hardshell cap (did that for a year and half long trip around the country), ends up being common sense. Don't keep your gear in shape, don't use it wisely during big weather, you end up with problems.
