One thing to pay attention to is the "cut" of the pad. Many of Thermarest's pads were recently changed from rectangular shaped to having rounded corners. I found that the rounding at the head end meant that my shoulders didn't comfortably fit the pad since they hit at its narrowest spot. (I sleep with my head completely off the pad, using clothing on top of my shoes or pack as a pillow placed at the head of the pad.)

A pad that is rectangular, at least at the head, might let you use a 25-inch wide pad. The Big Agnes Q-Core or the NeoAir All Season are two examples of rectangular pads that might work in a 25 inch width. I've used both in 20 inch widths and found them adequately wide. The QCore SL is a newer, lighter version of the QCore that is advertised as having the same R-value; the gear junky side of me says that I may have to try it one of these days.