Well thermarest.com does not list their prolite xs either, but a few places are stocking them nonetheless.
I did think of cutting a regular size in half, since I couldn't find any smalls in stock anywhere. Now I have a small on order though.
It doesn't seem like it would be very difficult. With the regular at:
14 oz. and 72" long /2 = 7 oz.
+ maybe .5 oz. for the weld…
and a 35" (-1" for the weld) length, that's only 1.5 oz. lighter and yields less insulation area for around the head area (see my previous post). However, the large size could maybe yield:
(2) 38" x 25" pads at less than 10 oz.
At roughly the same weight as the production small, anyone who was looking for a wider pad for extra insulation or rolling room may be tempted. For the hard-core SUL honeymoon couples, not willing to sacrifice comfort maybe they could share one of these?