If you're wanting to hard wire it, why not wire it to the battery with its own fuse? That way it's a stand alone unit and won't put too much draw on the fuse panel. I understand that running it by means of the cigarette lighter utilizes the fuse panel, but if you're wanting a more reliable setup, perhaps wiring it to the battery would be better. Just follow the fuse size it recommends with the inverter and you should be fine. There are a lot of different ways to run a separate circuit like that with the various fuse types on the market. Just a thought.
