Alternatively, if you like having the two volume pots, there
is space between the two knobs to fit a mini toggle switch. You could just stick your choice of cap on it for a fixed value no-tone/tone rolled off option.
Just a thought - I've done this on one of my son's guitars.
Major edit:Actually, Travis' suggestion is a really good one - I can see it working really well on this guitar.
Here's a drawing:
If you use a double decker split/pan pot, you can wire the bottom deck like the top half of the image, and the bottom deck like the bottom half.
And you could use another split pan pot for a single volume control knob, controlling both pickups.That way no changes to your guitar, no extra holes, you still get volume control for both pickups via one pot, and a really versatile tone control on the second pot.
Sccratch my previous comment - if this was my guitar,
this is how I'd wire it!