A2, I've been wantign to do this for the same reasons as you...it's a pain doing both. questions, 1) What did you do with the straps on the pack? 2) How did you mount it onto the protector? Great job!
You can see the slits I cut in the protector for the top straps, the bottom straps loop around the edges. Criss crossed everything in the back, hooked it all up, a few zip ties to snug the straps up and keep them tight to the inside of the protector. The front bags are zip tied on using available holes on the protector. Zip tied the ring on the shoulder pad for the water pouch line.
Will try to get an inside photo for you.