Funny. Now my post doesn't really make any sense. Oh well, I'm going to temporarily boycott editing my own posts.
Yeah, I'm thinking some simple 1/2" or 3/4" flat webbing for the cross straps (source? - not sure yet).
A key feature would be to allow for the corners of the inner tent body to be able to attach to the corners of the groundsheet strap system at the pole grommets, which would be staked out independently of the inner. This could be accomplished by simply making stake loops on the strap system and slipping the inner tent pole grommets UNDERNEATH the strap system, as it holds the pole terminus.
This type of setup would allow you to not only set up fly-first with almost any tent, but also make it so that you could enlarge the size of your vestibule during the day time when you don't need all of the tent floor real estate, in order to make it easier to 'work' (cook, clean, dry, etc.) during storms and you are sitting up rather than laying down. You would simply have to unhook the corners of the inner tent and slide back the tent floor and groundsheet, if applicable.
I believe the HIlleberg Unna uses this kind of system, since it contains no vestibule, but has a large floor area for a solo tent. From their site:
"Rather than a vestibule, the Unna has a spacious interior that easily accommodates the occupant and gear – or, in a pinch, the occupant and another person. And by disconnecting a corner of the inner tent, one can create both a virtual vestibule and keep the inner tent dry while entering or exiting in rainy conditions."