I highly recommend and use relays for additional lighting and equipment loads!
They are very cheap and will eliminate running the amperage load through the switches.
Just a suggestion -
Use 2 relays, one for each set of lights. I would suggest a 10 ga wire that feeds power to both relays from the 12v source. The 10 ga wire can be protected by either an inline fuse or an auto reset circuit breaker, also very inexpensive.
Run a 16 gauge wire from the 12v source to both switches and again, protect the wire with fuse or circuit breaker.
Run 12 ga wire from each relay to the set of lights it controls.
The net result is that the switches now only need a tiny amount of amperage to energize the relays. When the relays are energized, this closes an internal contact, and allows a direct current flow from the the 12v source, through the 10 ga feed to the relay, then through the 12 ga wire to each light set.
More trouble? yes! However much better than running higher amperage loads through the switches themselves and also results in a little brighter lighting due to less resistance. I do a lot of work on a variety of streetrods and related stuff and this is cheap insurance against meltdowns!