AFAIK it is an adaptation that bat wings (unlike AFAIK all mammalian gliding membranes) are uninsulated -- they are well vascularized for cooling. After all, bats don't have air sacs.
I don't know of any small, uninsulated, terrestrial endotherms.
About other things in this thread --
I don't think that pterosaurs and theropods are particularly close. I wanted to write that feathers (protofeathers, dinofuzz...) may be common to all ornithodirans. See http://www.dinosauria.com/jdp/archie/scutes.htm. (Cites 3 postings to this list from 1995.) I should have compared pterosaur fur rather to *Sinosauropteryx* protofeathers (but even these are branched) than to the new one's.
Pterosaurs as prolacertiforms? The evidence is accumulating, but is it more parsimonious than a single origin of the air sac system?
From what I know (not much...) all terrestrial crocs can be viewed as no more "warm-blooded" than monitor lizards. The pan-Laurasian Palaeogene *Pristichampsus rollinatii* was apparently an ambusher, capable of tremendous acceleration (and, at high speeds, bipedality), but not long-distance running.
But I _am_ interested in the "little hairs" on the underside of alligator throats...
AFAIK only one crocodylomorph, *Gracilisuchus stipanicicorum* (the basalmost one AFAIK), is thought to have been bipedal (others say semibipedal). I don't know anything about hallopodids, except that they are from the Morrison formation, Marsh classified them with coelurosaurs, and they are now regarded as the last sphenosuchians or suchlike.