Welcome to the forum!

It sounds as though you know what you want, and the selection sounds pretty good to me. I personally prefer a lightweight single wall tent to a tarp and bivy, but that's just me (also, I'm looking for another dog, and for solo backpacker plus dog a tent seems to work better--hard to squeeze a dog into a bivy when he's getting attacked by bugs!). I have also made the switch to cuben fiber thanks to ZPacks. Of course they had to go and develop their Duplex after I already bought a Hexamid Twin!

With the larger tarp, you wouldn't need a bivy, but then you'd need a ground sheet (which I'd get anyway just to keep my gear out of the mud) and a bug net. The bug net, if not too skimpy, could be used for two. The combination, from the research I've done, wouldn't be lighter than a ZPacks tent--I don't know about price, though.

You may find a few useful ideas in the articles on the home page of this site, especially the left hand column.