So many ideas in here ... and diagrams. Love the strobe umbrella backpack!
I know your event has passed, and I'm no pro, but I thought I'd share these so you can see something I've used before with some success. I agree that the OP's first idea is just too unwieldy. It would drive me nuts. I also agree that with the tightness of the beam that close to the flash face, you need to tilt the reflector into the beam a bit.
This takes about 2 minutes to devise, a simple card with a pinch in the middle I put a staple in to cause it to bend into the beam a little, then attach with a rubber band. The flash is pointing straight up, so no direct flash is introduced and you get a lot of soft reflected light from around the room. It is not tilted here, but when I put it on the camera it was tilted and aimed at the ceiling with the camera in vertical orientation, as in the OP.
|IMAGE IS A REDIRECT OR MISSING!|
HTTP response: NOT FOUND | MIME changed to 'image/png'
At my son's right was a window and we just got 8" of new snow and it's bright as heck, so this is working as fill flash. Here is direct flash, Canon 350D and 580EX (yeah, old, still works). Everything on straight auto, this was quick and dirty.
This is direct flash. Note the shadow on his left behind him.
This is with the little bounce card in place, flash pointed up to the ceiling, again on straight auto. Notice the softer shadow behind him, and the difference in exposure on the cabinets that were about 4 feet behind him and generally softened contrast. Overall, I think it is a much softer, more attractive look. Obviously he was not thrilled being my model.