That is what I ended up doing also. Shape Charge with a Sherman when needed and the 44 Mag on a 26" frame. If I cant fit it all in a 44 mag, Ill walk back to the truck to re-up.
That's almost exactly what I am running, I can swap the Sherman between packs in a few seconds. I keep my First aid kit and possibles kit in it, so I can swap packs and never be without my "minimum" of gear.
Pull outs are the same deal.
My Shape Charge is setup:
Small pocket inside on MOLLE panel
Small pocket outside on molle panel (Fits easily under sherman pocket and can be removed easily if not needed)
Small pocket on belt
Water bottle pouch on belt
Sherman Pocket
44mag:
belt has small on one side and a water bottle pocket, medium on other side (Medium covers my holster), .
Back MOLLE panel has a large pocket up top and a Claymore down at the bottom
Sherman rides over the large pocket
Inside I have a Small MOLLE pouch on the panel.
Shape charge is good to go for up to 40 or 50 lbs easily. It will run my day gear, optics and with some re-arranging a smedium boned out deer.
44mag EASILY carried all my day gear (including snivel gear for bad weather) optics, and a good sized boned out mule deer buck. 3-4 days worth of gear is easily doable and if you don't mind strapping the light stuff to the outside, packing out the gear and a boned out buck is not an issue.