Hi Greg. Looking forward to seeing what you come up with, I had quite a chuckle reading through that .
Those motor mounts do look really strong and beefy, I guess it depends where you want the compromise between weight and strength to be. I can show you what I've done for mine so far (and by no means am I right) I used a hole drilled into the HDPE chassis that snugly fits the motor with a polycarb plate (what I had available) on the front using the standard bolt holes. Probably weaker, but hopefully a little flex if there is any may prevent something else breaking elsewhere (that's my story and I'm sticking to it!)
20161016_170540.jpg