I'll echo a couple of the other commenters…
If you're considering a shelter like the Trailstar (or Trailstar mini), these provide a good bit of coverage so you don't need to rely so heavily on a bivy for weather protection. Instead it's main purpose with a shelter like this is to offer some wind/bug protection, perhaps a little splash protection and can serve as your groundsheet (no need for the tyvek then).
Because these bivy's aren't doing full weather protection duty, folks opt to go for a lighter water repellent but breathable (DWR) bivy over a fully waterproof (WPB) bivy. The DWR style bivys tend to weigh significantly less (5-6oz is pretty standard) than WPB bivy (probably most start around 16oz and go up from there).
You still get a waterproof floor (usually silnylon or cuben) with the various DWR bivys but the top half of the bivy is constructed out of various materials that tend to breathe better than the waterproof fabrics but that actually still also do a pretty good job at repelling light spray, spindrift, etc.
Lot of top materials to choose from in this regard… pertex, M50, M90, etc. I'm not sure on how they rate compared to one another, my hunch is that in the real world they're all fairly comparable. Of course the most breathable of all is a bug bivy (solid silnylon or cuben floor/sides with bug net top).
If you truly want a fully WPB bivy, I'd agree with Stephen that an eVent bivy is the way to go.
If you want to look at DWR bivys, most of the cottage companies offer their own version. I have a bivy from Katabatic Gear. My GF has one from Borah gear. Both serve their purpose well.
A couple of final notes… you mention being tall:
– Most of the cottage gear makers offer their bivys in various length and width options, so you can get it scaled to your liking.
– I've read somewhere (perhaps the Trailstar mini thread) that the trailstar mini might not be big enough for taller folks. Maybe check with Ron at MLD before you commit to this shelter… or go for the "normal" Trailstar. I use one and love it; although I have yet to use, or need, a bivy with it.