Hi Andy
I am not sure why you should need a template for the side panels. I have replaced a few veneered panels simply by removing the old veneer, cutting a new piece slightly oversize and sticking it on. After the glue has set, the veneer can be carefully sanded (or “dremelled” in the more awkward places) to establish the correct profile around the plastic backing. Always try out this process on a spare panel first - if you have one.
Good luck
Geoff