As said earlier, the Stalker is not practical. Especially for a trip of any real length on buckled Arizona roads! There is only about 1/8″ of padding on the seats as built. But this is easily improved.
I found a very inexpensive Memory Foam mattress pad at Overstock.com. This gave me enough material to add 2-3 inches of padding to the seats and plenty left over for the various pads that I will add to the knee knockers on the frame.
The overall effect was to great increase the comfort of the car without adding more than a few pounds of weight.