Yes, GigInk's plates are "no frills" regarding ply & bevelled edges etc., but what they do offer is a custom plate, any artwork etc., etc.
Had a few TRC's & 'plates off them for various RickenFaker's, and would be the first port of call for anything like that. Tim's a sound bloke.
He'll email a 'plate template to you in A4 PDF format, print it out at 100%, check your sizes/requirements etc., scan & email it back. A few days later, you'll get a scratchplate back to your design.