I'd go for something straightforward - nothing too complicated, so why not LSP - as in "Lawson's Sleeping Pad".
1. With something this short, it's easy to make a logo AND
2. Three simple letters as a name is very easy to remember (everybody knows what TNF or MSR means, or -in another context- KLM, KFC, JFK, etc.etc.).
It even has a slight resemblance to LSD - although I don't know whether that is good or bad :)
PS. If you like my suggestion (and therefore I'd be in for some pads), I wouldn't count on free shipping (as I live in Spain).
Edit: You might even want to think about MSP (as in Mountainfitter Sleeping Pad), but maybe that's too similar to MSR (or MSRP).