how hard to create cavity at the back of the bass?

[stoneroses]

The idea of getting a stingray clone and modding it has been dancing in my head for quite a while now.
i think about it b4 i sleep,on my way to work and at work.
I have two choices .

AXL:
one tone control one volume
solid alder body
no cavity at the back
passive pickup
costs $165

OLP:
two tone controls(one for each single coil), one volume
bass body
cavity at the back,but I heard hard to incorporate active electronics in here
passive pickup
costs $255

I like the AXL's wood,but its features really fall short of with the OLP offers.cavity at the back(convienient for putting wires) and 3 controls gives more options when I upgrade to an active setup.The again,since the AXL has no cavity dug at the back,it offers more potential?How much would it normally cost,or how difficult will it be for a hole to be sawed out?
Further,I would like to find out how much will two knobs on the AXL handicap the upgrade ?Will the $90 difference cover the lack of the tone knob and the cavity?

[Hambone]

To get to the topic question, it's fairly easy to make or reshape a cavity in the back with the right tools. A router with a milling bit or a pattern bit and then, for ease, a binding ledge cutter. You've got to really plan your cuts because of their severity. Keep in mind how the knobs are to lay out and never cut more holes than you have pots, swithches, or jacks to fill them.

I've cut these freehand if they are simple and I've used routing patterns from ½" - ¾" mdf and aluminum. It's better to pattern the cut than take a chance on a miss. A router at 10,000 rpm will cut a squirrels nuts quick as a wink