It's a bit late, but I can confirm you do not need to replace the dash. Under the "transporter" logo on your dash is the airbag logo, so you should only need the airbag and loom
I haven't had a chance to take the dash apart to confirm if the loom is present, but it's not present where the on/off switch would go
(Posting for other people who may be interested in the future instead of creating a new thread)