Can't comment on where to fit as I did mine myself. If you're ok with home diy try it yourself it's not difficult. Took me 2 hours with no prior knowledge.
I've had a powrtouch and purple line. Both worked without issue but if I was buying again I would probably go with powrtouch as the rollers get better grip in the wet.
The best mover if you have a chassis with the "M" mark is the Al-Ko Mammut. It is completely above the bottom of the chassis so no clearance issues. The down side is about £1500 fitted
I had a fitter recommended who put me a Powertouch Evolution on. He sourced the mover and fitted at my storage place in Rotherham. He is based in Sheffield and I was delighted with the job. If you send me a direct message I will forward his number
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets