Welcome to DCT
@Drbwell
The search engine on this site sucks- trying "Subaru" got a few hits but I didn't see any on the Legacy. I do remember there being some discussion of the "Eyesight" sensor pod on one or two of those threads, IIRC regards to mounting. Probably different cams involved, but they all mount and work similarly. Again I might not remember correctly but I think someone did a mount on the bottom or that sensor pod. There's generally 3 things to watch for when doing the front cam: Be sure it's where the wipers clear the view; be sure you can dismount the cam, access the card, and cables can be ran without hitting something; and most important is that cable routing does not interfere with airbag deployment.
You can probably find a vid on a very similar car which might help. If you're still not certain you can always use blue painter's tape to hold the cam in place temporarily as you check how everything else fits and works. And almost any car audio shop can do this for you if you're still uncertain about it all.
I would recommend doing a "blue tape" install and not replacing any pulled trim on the rear cam cable routing until you start the car and drive a block or two, then check your radio on weak stations and check keyless entry range with the cam operating. Sometimes there is interference found, and re-routing the cable or relocating that cam is necessary to mitigate that. Doesn't always happen, just something to be aware of. IMHO the DR750S is Blackvue's best cam overall, very reliable with good enough video quality and darn few problems reported compared to their newer models.
Phil