Missed a few posts... One "future-proof" question I still have with the 1080p (5805 MkII version) was whether there's any way to tell if the upgrade supports 1080p/24. [None of my other gear does, but I anticipate the 5805 staying in my system much longer than my other gear will...]
Also, by double box, I can only imagine putting another layer or two of cardboard around the original (store-bought) box; that's about all that would fit in my car's front seat. Were you really thinking of packing it in a box even larger than that, stuffed with peanuts, for example?
[I once tried out a Parasound Halo amp and pre-amp, had it shipped from way out east and it was pretty amazing how messed up the shipping cartons arrived. Physically the items were ok (the amp weighed about the same as the 5805). The pre-amp was really flakey though, perhaps due to the rough handling it had, though it only weight about 20 or 25 lbs, as I recall; the amp had a slight hum too - at that point I decided I just wanted a receiver, thus eventually the 5805. Can only imagine what the boxes looked like when they arrived way back east again (although I applied excessive amounts of tape to maybe hold them together a bit better for their return voyage).
Partly why I hesitated / ruled out a shipment to NJ (the other part was the cost and not knowing whether I'd ever need/want 1080p... guess I do). CA may work out a little bit better.]
Pretty close to taking the plunge, though already going through withdrawal symptoms just thinking about it...