Richard, this is the kit I am thinking of purchasing. One switch with 5 heat position settings per seat:
2 Seats Install Dual Dial Switch Seat Heater KIT Heated Seat Ship From Australia | eBay
You can get them with individual switches too and they give you a silver trim bezel which would look good in the Pace, although they only have 2 settings:
2 Seat Install Round Switch Seat Heater Ship From Australia Silver Ring FOR Free | eBay
By the way, are you fitting more of the sound deadening material in the cockpit?
Cheers,
Simon
PS> it's all looking great!