Adding dashcam battery pack via relay

I bought a battery pack for my Dashcam. The instructions say to just add a fuse tap directly off a circuit in the fuse box. I don't think pulling in 25W\9A on an existing OEM circuit is a good idea. I want the dashcam battery pack to only get power when the ignition is on. I also do not want to draw the full load through the OEM wiring when the engine is running. I've added lighting accessories before with a relay harness. I think i should be able to accomplish this with the same thing but I am not 100 percent on the switch connections. I've drawn up a diagram that I think is right, but I am not an expert with electrical. Is the following a safer way to accomplish what I am after?

 

How do you plan to not draw "full load" when engine is running. What does "full load" mean? If you don't want to draw through the OEM wiring, use a stand alone fuse/relay panel. The battery is going to charge at the rate of whatever is controlling the charge, via OEM wiring, stand alone relay or otherwise. The power draw should be provided by the battery manufacturer. It's going to use a charge controller of some sort. How are you calculating your power draw. 25W 12v and 9A doesn't make any sense. The only way you can get 9A draw and only 25 W of power is on a 2.7v circuit with almost no load.

Battery packs for dash cams are for multi hour parking mode operation, like all day or all night kind of thing. Do you want 8+ hours of recording from your parked vehicle?

 

Power draw is per Manufacturer specs and shows as the draw in phone application provided with the battery pack. I do want to draw that full amount, but over a separate wiring harness not the vehicle’s OEM wiring.

Yes I want 8+ hours of recording from my parked vehicle.