That’s a great idea. I hung my holster off of one of the straps that click to the bottom, made for an awkward cross draw. I like this way better. A lot easier to get to. I’m going to have to try that this year.
I also run a Marsupial harness and considered carrying my 10 mm in similar configuration. The major factor I went against it is that the barrel points in a sketchy unsafe direction. In other words, you're barrel sweeping the immediate area/people as you turn. Goes against fundamental gun safety rules. If hunting solo maybe okay but not with other safety conscious hunters around. Unlikely shit can happen in the mountains.
Everything is a compromise for sure. I tried a behind the harness holster, pistol at a 30-45 degree downward angle. I wear my harness high and it made for a very difficult draw, and still left the muzzle pointed gut/waist level to anyone standing nearby. Just gotta find what works for you.
Doesn’t solve the barrel control for the neighbor but the velcro works really well for under the Kuiu Harness. I also just rigged the harness “bungees” under the velcro so even in some extreme velcro failure the bungees would still have to break. Been very happy with this so far for my P365 and makes for a really compact setup by having the pistol flush against the harness with handle coming out rather than the pistol flush against your belly.