summer sleep pad for hotter regions

Cots/hammocks are great for the summer. Obviously a cot is going to be unwieldy to pack but for the same 1.5 lbs your Prolite 4 weighs you could bring a simple gathered end hammock. You can even get them with bug netting. If you're bike touring another plus would be the ability to roll your bike under the tarp if it rains (if the tarp is large enough). I've only hammocked a few times but if I camped much during the summer that's probably the route I'd go. There's a reason hammocks are popular in the tropics I suppose.

Adam

I think your off base. The r-value of your sleeping pad is miniscule compared to your mattress at home (those things are like a foot thick!), and people sleep on those through hot muggy summers. It is possibly a breath-ability issue. A klymit might help with that. Other than that most backpacking pads are pretty non-porous. You should look into increasing circulation. Possibly a net tent and tarp or hammock.

I grew up in MD, and have sweated rather than slept through many a night like that.

I think your best option is a hammock. Since it sounds like you're open to the prices of a NeoAir (if not the function) I think you could assemble a basic hammock setup in that price range since your express purpose is less insulation and won't need to buy an underquilt or other insulation.

Hammock not only has zero insulation, it also allows any breeze to wrap all the way around you. Most of the time, this is a challenge to be overcome, but in your particular use case I think you'd view this as a feature. Comfy too. Be sure to get a full-enclosure net like the Dream Hammock Bug Sock to keep the skeeters off–they'll bite you right through the nylon of most hammocks.

Short of that, I think something like a Gossamer Gear Thinlight would be your next best option. Light and cheap, but certainly not comfortable. The thinner the pad is, the more gaps with the ground your body will have, allowing drafts to cool you off.

non-insulated air pad will probably be the coolest option on the ground; a hammock, if breathable fabric, ought to be a little cooler.

You might be right, may be more of a factor of a non breathable surface against me than the R value of my pad. This may rule out most pads. Mattresses have a much more breathable surface than plastic pads. I'll look at the klymits, very strange looking though.
Hammocks, good idea. I guess the price might not be so bad since I am looking at the neo-air but the gear closet is getting rather full. I'll have to try one out first. They never looked that comfortable, I am side sleeper.
The non-insulated one(klymit as well as others) might be the simplest solution. But will it be the right choice since most of them are have a non breathable surface.

Better idea: Just camp out west:)

Thanks folks