This is very late to be sussing out shelter options!
Personally, when I were a ground sleeper (hammock now) I really liked the bivy/tarp combo because it gave me the options to do cowboy or bivy (bugs!) or tarp only (hot, not too buggy) or tarp+bivy when things were really really messy, wet and cold.
My setup was (and I still have it for trips where GtG is mandatory) a Zpacks hex solo tarp and a clone of a Zpacks splash bivy. I find the center zip arrangement to be excellent.
Hexamid solo plus Bivy_SMALL_01.jpg