29 Palms, CA
I would say that 29 Palms is the closest town to the Old Dale Mining district. There are hotels that are real close by, but you can also camp on the B.L.M. land, and there are plenty of opportunities to do this.
About the bat cave, it was almost hidden from the main road in the area. You had to almost know where you were going in order to find these little guys. They don't get too many campers/tourists in this area of the Joshua Tree National Park. Because we were technically out of the park, almost nobody ventures in this area.
Camping? Why don't we all camp at Dan Wilson's house? He has a 20' X 40' pool, he lives about 5 houses down from Bob Hope in the swanky part of Downtown Palm Springs, he is a 'wheeler, he is divorced, and he has lots and lots of free time on his hands, so, having a few visitors stay over isn't a problem! We'll all have to ask him, but with his heart condition, he could not sleep in a tent, and he would feel bummed out if he couldn't be a part of the action. Or, you guys could stay in the park, and I could stay at Dans house. Maybe my wife would like to come along too. She love's 'wheeling in the desert too!