Seems like an escape hatch in the wing would be problematic; first, the wing has a top and a bottom surface so a single hatch would probably not work. Then, I've never seen a wing retain its' shape in a crash (which is why it's in the way of escape in the first place) so it would probably be impossible to release the hatch due to all the deformed aluminum.
The biggest drawback from the racer's standpoint is that it would add weight (and very high up, too, increasing the C.G.) and possibly be difficult to design so it didn't disturb the aero, both non-starters for a team to even consider it.
Fuel pumps in the cockpit have always bothered me, and moving them to a safer location along with a fire supression system seems like the way to go along with wearing all the mandatory safety gear.