Not really the answer you're looking for, but not sure why you'd want to increase your oil capacity further? 7 quarts is a LOT for a relatively small (3.0L) motor. That's one of the reasons they can get away with an extended oil change interval. By way of comparison, my 4Runner has a 4.0L V6 that only needs about 5 quarts.
Further, if your car is losing oil, not sure a deeper pan would be the answer. If the loss is pretty drastic, check for oil leaks. If you don't see any leaks and are losing less than about a quart per oil change, chalk it up to the car just burning oil and live with it.
I also don't think a deeper oil pan would fit. My guess is it'd get in the way of your metal support brace/shield, which you really don't want to drive without. Just some food for thought.