I'm looking for a lightweight, low profile chest rig that can be worn comfortably under a heavy frame pack, for civilian wilderness trekking. To mount the pack properly, I can't have anything on my waist/belt (at least, not comfortably).

I'd like the rig to have pouches or holders for a handheld radio, GPS, flashlight, multi-tool, and ideally a zip-style flat pouch for documents or maps. An option for a pistol holster (full frame auto) would be nice, if such a thing exists in a form factor that a backpack can go over.

I've gotten by putting the radio and GPS on the backpack's shoulder straps, and the flashlight and multi-tool on the backpack's belt - but for some of what I'm doing I need the option of shedding the pack while keeping essential and sensitive items on my person.

Coaxsher makes something that looks to be close: https://www.coaxsher.com/Radio-Chest...ss-p/rp203.htm, but I have no experience with this brand and no idea what else might be out there. I'd appreciate any suggestions or advice.