If you're mounting pots to the PCB, and the pots have standard length legs, most toggle switches will be slightly taller than that and won't fit under the PCB. Here are some approaches I've used:
1. Mount the toggle to the east, west, north or south of the PCB (see photo with one to the west.)
2. If your enclosure is deep enough, use pots with extra-long legs which will allow the toggle lugs to clear the solder side of the PCB. Or use solder-lug pots and wire them to the PCB holes, which will give you more clearance under the PCB for a toggle. You can use flexible wire, or just add three long straight legs made from clipped resistor legs.
3. If your enclosure is not deep enough for (2), try a deeper enclosure. Example: 1590BBS is 9mm deeper than 1590BB, with all other dimensions the same. 1590T is even deeper, although slightly narrower.
4. Mount the toggle on one side of the enclosure, as seen in many JHS mods, there's always room if the toggle sits in the battery space and your use external 9V power.
5. There are low-profile push on/push off switches that take a round hole and protrude less from the side of the enclosure than a toggle, the one in the pic is 4PDT and has an LED indicator. Search the part number at Mouser, Digikey, Newark, etc.
6. Make a PCB with holes for the toggle wherever you want it, the body heights of toggles and pots are similar enough to accommodate.
