In cab fuse panel question

I installed recently my boost auto tow mirrors with spotlights towards the back on my 2018 SR5. They originally were recommended by boost auto to be hooked up to the back up lights but I didn't like the thought as they are too bright. I tried to hook them up so they turn on when I turn the cargo light switch to on only but because that switch only runs a relay I would have had only the option to have the lights on when switch is to off.
I found on the fuse panel inside the cab a empty spot that has power even with ignition off. I used a tap a fuse and connected my my spot lights via a switch to that location.

Are empty fuse spots on the fuse panel safe to tap in? How can I find out if they are meant for add on accesories?

My fuse panel only shows a not used spot. I looked at fuse panels of newer models and they are different.
I didn't want to tap into anything that was existing. I have seen a lot off threads here in the forum where people ask where they can tap into for bed lights etc and there hasn't been a clear answer.
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Drove the truck and everything looked ok and was working as it should. So its worth it to look for empty spots on the in cab fuse panel if you want to hook up permanent power. Who knows where that empty tab runs to. I put a 3 amp in line fuse in before the LED lights just in case. I rather replace a 3 amp fuse then running the risk pf damaging something unintentionally.