Thanks for the great advice. What I'm planning to do is continue with the paleo, introduce some short fasts (I tend to not do too well without food but maybe it's psychological), and supplement with carbs as required. Reading some posts here and at CF, it seems like running a paleo diet with some compromises to modern patterns of exercise is ok. By compromise, I mean some carbs during a longish workout or game (Cytomax for instance) followed by PWO protein/carb shake. What I have been largely avoiding are the gratuitous bad carbs that otherwise sneak in during the day as well as most dairy.
I have a feeling that if I stick to Paleo and dial in the carbs/protein supplements as required, it should be possible to gain some mass while leaning out. Anyone disagree? It also makes me feel pretty good -- somehow I'm rarely hungry with the Paleo intake.
Another way of thinking about this is Paleo for the basal and lifestyle metabolic burn (some deficit, maybe 500 cal per day) and combining it with carb/protein supplementation for the exercise component (replace calories burned in exercise with supplementation, taking care to maximize the benefit through the right timing).