I'd like to add another volume and tone control to my yamaha rgx520fz (clicky) . I've taken of the back cover, and the cavity that stores the current volume, tone and pickup switch isn't too large, so some routing would have to be done. How much would this loss of wood affect my tone? And can a coil tap be installed without switching the pickups? I actually really like these stock ones.

I'd get this done by a pro, any estimates on the cost?
Yamaha RGX 520FZ
Squier Affinitys Strat (customized!)
Johnson 620 Player Acoustic

Boss HM3 hyper metal
Boss CH1 super chorus
Zoom G1X

Peavey Valveking Royal 8
New: Peavey JSX Mini Collosal
If it doesnt have the the wires on the pickups for coiltap isnt easy to add. So if you want that you would probably have to buy pickups. And you can buy concentric pots where the vol and tone for each pickup could be in the place of one knob. Have a look at warmoth they have a good selection of knobs and pots for this. Wouldnt have to route for these.