I made it up to the Fargo, N.D. contest last weekend (8/27-28) and Glen Nyhus had this conversion handle for sale. He generously donated one to the raffle (they had a separate raffle for each event, and each flight in that event got you a raffle ticket in that raffle -- a very cool idea). Anyway, they paired the conversion handle with a Brodak Guardian kit and I won it. It seems a very sturdy unit and I'm now considering building the Guardian as an electric for it.
This handle uses a steel strap that bends from the top of the grip part and down through the battery box. It may be a little difficult to discern in the photos, but there is a U-shaped frame around the trigger to give room for the trigger to operate. As stated, it seems plenty strong enough and when I get it into flyable form, I'll post some more photos.
Glen had a few of these finished and if anyone is interested, I'll forward some contact information. Oh, this includes a LiPo in the battery box and he was asking $50. I'm posting this as informational and I don't have any stake in this enterprise, other than to inform fellow competitors and as a Thank You to Glen for the donation.