I ended up going with the Lowepro Vertex 300 AW. Probably about the same size as the TT Airport Accel, but a bit cheaper (Lacks the separate removable laptop sleeve, but adds tripod attachments). From a bit of a packing test today looks like I can get everything in it but the 8" dome, tray/handle, and the laptop itself which just feels a bit too 'tight' in the pocket for comfort (afraid I'm flexing it). But all lenses, macro port, housing, 2 bodies, 2 DS50s, sync cords, assorted batteries and chargers, and even the flotation arms and clamp pieces all fit. With just a dome and tray in with the scuba gear (dome totally engulfed in a wetsuit, naturally!) I don't think I'll present too bad a theft risk, at least no more than scuba gear in general already does. Wife can take the laptop bag for her carryon, and we both still have our 'personal item'.
Could probably fit the laptop too if I were comfortable taking the back off the Ike housing and transporting that way to save a little depth. But seems too dangerous to the controls.