John,
I am not a big fan of over lapping panels. First you need to make one panel have and offset, joggle, to keep the fit up smooth and then every time you want to take say the top panel off the bottom one drops also and my bet it that it is a SOB to get them all lined up and fasteners inserted. If you have a line of separate fasteners for the top panel and the lower panel then you can remove either without having to mess with the other. When you are in the pits and it is 100deg F and you are hassling with getting all of the fastener holes to line up and the panels to stay in place you will probably re-think your decision. To me it is about making everything convenient to access. Installing fasteners take time but pays it all back at the salt. Also things like your front panels that cover everything forward of the driver, split them so that you can remove the top to get at things you have buried in the front. If you make the front so it is a single long tube then to get at anything you will have to take off the front axle to slide the panel forward. (Don't ask how I know this!) When Duke and I first got our car it was mostly held together with 10-32 flat head screws, literally hundreds of them, so we vowed that we would make as many panels as possible be held by Dzus's and be easily and quickly removable. A lot of work but it pays of at the Salt.
Rex