piro, wear your 7mm AND your 3mm. I have a hood you can borrow, might be a bit tight on you. I have some thin gloves as well, might be some help.
btw, I dove 48 deg in 7mm last year. it was fine as long as I stayed shallow. If you've got most of the day to spare there is another option, we could drive a couple of hours and dive with the guys at Clark Hill Lake. I dove there a couple months ago, the vis is much better, there isn't a muddy hike, and believe it or not the water was noticeably warmer! those guys are diving in 7mm suits.
tim, yeah sinking ankle deep in mud in doubles doesn't sound like fun, not in my nice clean new drysuit especially. If I've got to hike it, I think I'll just go get a couple of AL 80s and dive in recreational gear for a change.