H Danny,
I had a Sidepower unit fitted about 5 years ago.
I contracted with Angus Simpson (Davis's Boatyard) to glass in the fibreglass tube below the waterline, fair it in neatly, and fit a watertight bulkhead, in the event of failure or collision.
Purbeck Marine (in Cobb's) obtained a Sidepower unit, and did all of the physical and electrical installation, including a battery next to the unit.
I was happy with both, they worked well together.
The unit itself has been wonderful. I could park Feisty without it, and did so for a year, but it's so much easier with a bowthruster, particularly in confined spaces, and in tricky conditions, such as strong side winds catching the bow at the last minute.
Mike