Glenn I believe my 5/8 pad weighs around 12-16 oz, the 3/8 would add 9 oz. Still lighter than my BA air core is. The bulk is also my concern. I could always buy/cut the 3/8" pad down to 48" long to cover me from the hips up. That would only add a few inches to the circumference of the 5/8 pad I already have.

I wont go above the treeline anytime soon. My hiking partner (bro-in-law) has a hammock and loves it. Im a tent guy myself, I love the secure feeling they offer, weather, bugs and the like. By the time he packs two straps, hammock, tarp, rope and pads his weight is only a pound or so less than me with a tent and pad. I like to stay under 25# total pounds for anything 4 days or less. Im a real stickler about dead weight!