Thanks for all the replies, I've searched a little more and found Audiophile Engineers in Tampa. They really seem to know what they're doing and know Robin Butler who was recommended here (again, thanks!). I'm going to their shop next week and pick their brain. I know (is it Mark?) is super busy and that's the holdup on the DCON 10"s, I might just wait a few weeks and see if they're back up to production and have AE build a good box.
I've spent a little time on the 12volt and bcae1.com to learn a little more, I might just get "The Loudspeaker Cookbook" this summer.
As far as max dimensions the biggest constraint is height, no more than 14" tall which makes a 12" driver a tad more challenging.