Alan -
Nope, no access other than a cut out for the battery box to rest on a piece of closed cell foam. It's right at the 2x3 that holds the rear of the deck on the brackets.
My boat is relatively shallow, so while I wanted a raised deck going off of the seat height was too high for stability - so I made the deck start at half the height of the front bench. Deck height from the bottom of the boat's "V" is only about 4-6" or so, so there's not a lot of usable space under it IMO. The real benefit was that it gave me a flat floor to use instead of a "V" to stand on, so it really added like another usable 4' onto the front of the boat.
Right where your cut out is, the battery box would be up against the seat with the top showing, then a seat pole with the the seat on it (just over the top of the battery box), then wide open deck until you hit the bow cap, and under that is a cut up 5gal bucket to hold onto my anchor. Still easily out of the way, and VERY comfortable to fish from as my brother in law was so happy to inform me. :|