garygid wrote:Question is, can one remove the rear "bottom pan" in the field to be able to acccess the tire in roadside conditions?
No, the rear under-body panel would stay in place, but modified.
Are you thinking of using a "standard" crank-down mechanism installed in the floor of the cargo area?
Yes, standard crank-down. There's no need to reinvent the wheel
The actual crank access will likely be the right rear corner of the car, under the bumper.
Or, add a "tire well" and cut an access hole (and add a "lid") into the floor of the cargo area?
Yes, a simple "wheel-well", just like an airplane. A 30 inch diameter tub and a cut-out in the rear under-body panel. Super simple. No lid, or "gear door", as the airplane world calls it. There are plenty of fast airplanes without gear doors in a low drag area.
From the pictures, it looks like the Quest tire is narrow enough to fit, but that the stock LEAF tire is a bit too wide, even though the LEAF tire's slightly-larger diameter would be OK?
There's no intention to carry a spare full size tire, but you could, I guess. It would hang a bit out the bottom (not a big deal... look at mufflers hanging out the bottom of ICE cars!).
I just included the picture to show how the sizes compare. The Altima spare tire will be slightly larger in diameter than the stock tires. I just needed to know the LARGEST diameter likely spare tire to spec out the diameter of the wheel-well.