I use the same batteries in two or three ships so the pre-configured tray idea won't work for me. I put Velcro on the full width of each bottom frame cross member and on the front part of the tray area. I then cut a piece off a cardboard box that is the exact dimension of the bottom of the ship's battery tray and about an inch longer. I slip this cardboard 'template' all the way into the tray. Then I just slide the batteries in to where the rear battery should be for CG. Hold the forward battery and pull out the template. The batteries fall into place on the Velcro.
I strap the batteries over the top of the battery and around the bottom of the frame using the supplied Synergy battery straps. I found that easier than trying to run the batteries over or under straps that were pre-installed through the small strap slits in the CF frame.
I remove the batteries by pressing up from the bottom to loosen them from the Velcro and then just pull them out keeping the front of the battery high to avoid snagging on the Velcro. This system, for me, is nearly as fast as the removable battery tray on my Align 600 EFL Pro. This or a similar method may be common knowledge for more experienced folks, if so, forgive me if I think I've discovered gold here....