In gliders, I found the best was to just velcro the RX and RX battery in place. There's normally not enough force on them in flight to make them move. There's no engine vibration to worry about. And in a crash the velcro releasing will spread the impact over a longer time, (which is the only reason for padding in a glider)

You want the battery semi-removeable. It doesn't have to be easy to get at, but you don't want to have to cut anything to get it out. We normally recharge with the batteries in the plane. (the switch harness has a charge plug) In gliders, I put the switch inside the canopy (if it comes off easilly without removing the wings....) and then you can't accidentally turn it off when launching.