I am running a few relays, under my hood, and all 3 need a switched 12v source. I am hesitant on spicing into my ignition wire multiple times. Even though, the accessories won't be drawing a ton of amps it seems like a bad idea.
Use a fuse tap on a switched fuse in the fuse box to control relays for the other items. Run a fused lead from the battery or the 12v+ in the fuse box to the relays for power to the devices. If you need a switch in the cabin, wire the switch between the 12v switched tapped fuse and where it powers the switched side of the relay.