I think a joint weekend with the WEC is a good thing, as long as it is done right. Sebring is a good choice of venue for it, but the day and length of the WEC race are not! The WEC should put on an into the evening 6hr (normal WEC round) race on Friday, 1-7pm or 2-8. That would allow any surviving eligible teams an opportunity to refresh and join in on the IWSC Mobil 12hrs of Sebring race if they wished.
L.P.