I'm not well versed in P60 drop-ins but if you are up to it, you can build one yourself. A 2AA driver/3v + an XM-L on a round MCPCB + empty P60 drop-in will give you want your want. There are only a few points to solder and should be pretty quick to do.
There are also some budget P60 drop-ins with 4.2v max, those might have boost drivers, or were meant for 1 Li-ion battery.