But one more homerun wire is not much more work and less V drop. The fuse box is still in the running…At least now I see my way forward 
I took a look at the fire wall and did not see anyplace I would frel confident poking through. I have the charger clipped to the battery and the cable going under the hood and trough the door via the molding.
When I get my taps, switch and wire I will revisit the fuse box. The passenger side may be more accessible.The present arrangement seems to be working but with the warmer weather it is hard to tell.