I'm hoping to be able to dual use the trailer, yes. At least that's the plan.
Just curious as I read through the thread (maybe I missed it), but it seems like camper jacks would be the simplest solution to get the shell off the frame. As long as the floor and corners can support the weight from below, you don't have to build in a load path for lifting points that way. Campers use chains down to belly bars to secure the box - a foamie build would be light enough and the moment arm short enough that you could probably use ratchet straps.
I was looking at doing the same thing till my trailer began to morph into a bit of a giant for the foamie world. I was thinking about them for my own application and found a set of hydraulic ones for $100 on local CL. An even cheaper option would be to get a free camper (lots of them around, rarely advertised) and take them off. You'll also get a lot of the other little bits and bobs. The last camper I stripped out gave me all my appliances and windows and cost me $60 in dump fees when I was done.
A set of jacks brand new starts around $500 (eBay)
I'm enjoying the evolution of your door. An advantage of the octagonal (or round) door is that you'll have additional width at the shoulders when you're crawling in. I had thought about making my (6') door shaped like a coffin for the same reason, but it would put the hinge line on an angle that would always swing open. Then I thought about straight sides and clipping just the top corners, but square would allow me a bigger window so I went with that.
One thought: will you be able to get everything you need to in and out of the door in case something goes wrong later ?
Louella (eaglesdare) just posted about wrassling her new mattress into the trailer...had she not left it in the plastic till it was inside the door, it sounds like it would have probably gone in in pieces.
For me, a big part of the enjoyment is in the evolution of the design, so I'm enjoying reading everyone's ideas on this
I too had thought about a pop top at one point, but I took an idea from a Catalina 22 that I used to sail:
These move forward as they lift, but on your model the overhang between the edge of the roof section and the curb of the opening should give you enough travel to make it work. One of the best mods on that boat was to replace the fixed struts with gas shocks - mine took maybe a pound of force to lift and the shocks locked it in place when it was up.
Alternately, yours might be light enough to use a heavy window crank (scissor) at each end, though you'd probably still need stays at the side since it would be supported at only two points, though attaching the canvas under a bit of tension would work as well.
....back to lurking your thread now...
So, I have a question about the two point door latch. What holds the rods on? Cotter pins? Tiny ones? Or are they enclosed so they don't need them? Just wondering. I've never really looked closely at them. I still need to pick up the foam and the roller catch thingies. Eventually, I will need seals and such. Got a neat idea for the outside of the door too. 
He wants to see how it works. 
