The best solution would be to use an archival double-sided mounting material (like a giant roll of double-sided tape).
Although relatively unknown in the UK, there is a German product that fulfills this role perfectly being easy to use, not needing a Dry Mounting Press and has passed the Photographic Activity Test for archival materials.
Neschen Gudy 831 | 802 are pressure sensitive cold mounting adhesives in a roll form that can be used to make most any smooth surface self-adhesive. Perfect for mounting photos or other heat sensitive graphics gudy 831 | 802 can be applied without the need of heat or expensive machines. One of our most aggressive adhesives gudy 831 | 802 has a traditional construction using a non-woven paper center that is coated on both sides with our own high tack acrylic adhesive. gudy 831 | 802 is both acid and solvent-free and has passed the Photographic Activity Test (per ISO 14523) making it ideal for permanent archival mounting of photographs.
These mounting films come in rolls that are 2ft wide x 33ft long. There is nothing in the box but the roll itself. No release paper and no squeegee. No instructions either because they are not needed. Below are instructions to show how easy it is to use.
Roll out a sufficient length of the Gudy, place the print on it face-up and press down to make the print stick. Cut round the edges with a scalpel and straight edge. Peel off the silicone-coated backing, place the print on the mount board and again press down to ensure adhesion. When placing the print, whether on the adhesive surface of the Gudy as the first step, or subsequently on the mount board, it is a good idea to start at one end and then lower the rest into position bit by bit, firming down as you go.
You can order it from Monochrom in Germany here:
http://www.monochrom.com/Gudy-Kaltklebefolie-831.htm?websale8=mono-c&pi=1460
and I also believe that Firstcall stock it in the UK.