So I finally got a chance to move forward on this - bought a 4x8 sheet of masonite and managed to get it home in the back of my MIL's Ford Focus station wagon (with 2.5 feet sticking out the back!). This past weekend I cut the blanks and was able to shape the skins for one 30" straight, the 40" straight, and the outside of one of the curves (the one that caused problem #1). I still have to do the inside for this curve, both sides for the back curve, and both sides for the extra 30" straight (which I will use when I want a standalone setup with no bridges).
Anyway, between playing volleyball for my company's team, playing whiffle ball and flying Tyler's new little remote control helicopter (god was he excited!) I was able to snap a couple of quick shots of the 40" straight. Now the skins haven't been glued on yet - I just leaned them agains the platform to give ya an idea of how they will look.


I drew out the arches using a combination of free hand drawing and a set of french curves I was able to dredge up from my college years. (Note to self: post a picture of the templates.) I plan on gluing them to the sides once I buff down the platforms with my palm sander.
One interesting note is that I find I actually like the soft side of the masonite instead of the hard, display side because it really adds texture to the appearance. I tried to snap a picture of the difference, but the camera blurred it - I'll have to try that again later.
fife, Brent, I'll be hitting you up for ideas for finishing the joints along the top, and attaching and finishing the underside of the arches. It's going to be challenging cutting out the undersides for the curves - I'm actually cutting the curve to fit two dimensions instead of one. Not quite sure how I'm gonna do that.