Recumbent tadpole trike - rear engine mount?

I am a newbee and I apologize if I am treading old ground. I have searched the forum (and other forums too) though and not found the type of engine mounting information I am looking for. If there is a thread on this though, any help in directing me there would be appreciated.

I have a Catrike Trail (receumbent tadpole trike) and also a Subaru Robin 33.5cc engine mounted to a Staton, Inc gear reduction box. I would like to mount the Subaru and gear box behind the rear wheel, relatively low down (about axle height), but I have never seen a mount like this. Staton has a system that will mount an engine above the wheel, like this and also an axle mount. But the above-the-wheel mount puts the engine right next to your head on a recumbent, and I cannot use the Staton axle mount for other reasons. So, ideally I would be able to triangulate back with something pretty solid to mount the engine. But I have never seen a kit for this.

If anyone has a suggestion for a kit, or even just parts that can be fitted together for a rack like I am describing (maybe parts from McMaster-Carr or someplace like that?), please let me know. I am open to any suggestion. Thanks.

Thanks guys. Yeah, I would like find some sort of extension that would extend backward from the drop-outs, and then also, as you say, from the seatback supports (the rear legs). But no mounting parts came with the gearbox and Subaru. Dave's a nice guy, smart and he tries to be helpful. But to be honest I find him tough to communicate with about what I am looking for, even after sending pictures to explain it. He has some thumb-screws that I think are somehow supposed to mount to his "14-inch supports", but he doesn't have supports in different lengths, and it is not clear from his descriptions, how any of it would mount to a drop-out or extend for different lengths. So, any additional suggestions for mounting components that would be compatible with the Staton gearbox would be appreciated.