130mm hub on 135mm frame
The QR (on the outside of the dropouts) and the locknuts (on the inside) are what hold the wheel in place - you could have the axle ends flush with the dropouts and it should be fine (Sheldon describes this setup somewhere, with only the skewer going through the dropout, to allow perfecting chain tension on a fixie with vertical dropouts) - but 2mm axle projection vs 4 or 5 makes no difference. Definitely DON'T "spring" an Al frame to fit a hub of different width - generally ok with steel if it's only a few mm. If you want a wheel that's not available off the shelf, don't be afraid to build your own - it's really quite straightforward, again SB has the clearest instructions I've found (at least, they were what I started with) and you will very likely end up with better wheels for less money that a factory wheelset.