Quite a few se7ens have IRS these days. Caterham uses it in the CSR, Westfield has offered that setup for over 15 years, Birkin recently added it as an option, the WCM Ultralite uses it, and I'm sure there are others.
Regarding ground clearance, I was recently talking to the folks at Raceline about a dry sump for the Duratec. Their wet sump is level with the botom of the bellhousing, so although the dry sump increases ground clearance at the engine by 38mm, the bellhousing remains the low point - until now. They have just added a new low profile, dry sump specific bellhousing to their lineup that increase ground clearance at that point by 23mm. It requires a new fllywheel, but uses their standard 8-1/2" AP clutch.
-John