5 minute designs** (or there about 🙂 )
That sounds pretty cool. I'd love to see it when finished. I have personally always been a fan of small 2.1 builds.
I think I would try the smaller cap to begin with. I haven't used that tweeter, but I am willing to be you are going to get some audible distortion if you cross too low. It is impossible to say without really measuring it, but with a low order crossover, I think it might be wiser to try the higher crossover point first. Just a thought.
Here's another quickie.
The Dayton Audio PC105-8, 4" full range driver is on sale through today. I figured, why not do a quickie?
Put two of them in a 1 CF box (1/2" ply) with a 1/2" x 3-1/2" slot in the face, and it'll be tuned to ~53 Hz with an F3 of 41 Hz. Throw a tweeter between them for an MTM with an appropriate cross-over to get nice, almost full range.
Remember, this is about getting your creative juices flowing to see what you can dream up.
BTW, I just saw the PC105-4 and did a quikie with them. Same configuration leads to a smaller optimal box with both BF and F3 noticeably higher, but switching to the 1 CF box is all but identical with the -8.