Never thought about doing things that way, I had in my head to make an aluminum bracket to sit forward a little and use the Lowrance mount to bolt to that. What I had in mind would be solid to take the beating I give this rig with the dang wake board boats and heavy boat traffic I deal with. Yours may be a better idea and would make it possible to swivel some from passenger towards driver. I assume you mounted the foot in the rear of the hole and had the center shaft laying somewhat flat? That would be quick and easy if solid enough and my experience with the ram mounts has been pretty good.
GotMyAlly, I hope you took no offense to the lighting thing. On a 21 I have no idea what's being used so no comment, my point was the housing is more important and has to be designed for the bulb to work properly especially in crappy weather.