Peter, yes a substrate that is smaller than the print will solve almost every possible problem with glue mounting prints.
For canvases leave excess canvas all around the print area. Cut the substrate to the finished size for the mounted print one three sides, leaving the fourth short side of the substrate much longer than the prints. Align the print carefully on the dry substrate, then tape down the (short) side of the print to the excess substrate length. Roll up the print on an old roll core tube. Roll glue onto the substrate, 0.003 ounces per square inch (plus 3 oz to prime the roller if dry), then roll the print onto the glue. Then pat down the print with a cotton-gloved hand, or preferably run it through a roller. If it's a tough surface like canvas, feel free to swipe your hand across the surface. The overhanging print will protect the top roller or glove from the glue, but you need to check the bottom roller for ooze after each print. Then trim the overhanging edges with a matte knife. The biggest trick is applying just enough glue to get a good attachment, but not so much that it oozes down the sides. Spreading the glue out from the center of the board towards the edges, and then only hitting the edges after the glue is well spread out in the center helps a lot.
If you're using Gator, the mounted package will warp for about 8 hours, then straighten out perfectly flat. So Don't Panic.
On you first attempts, use scrap prints and try to rip them up after a day or so. It should be really difficult and if you're using Gator you should be pulling off quite a bit of the laminate if everything is AOK.
PS, if you're using Miracle Muck or LaminAll, the prints are theoretically removable by heating in a hot press for a few minutes, then immediately peeling them up. It really works, although I'm not sure how the passage of the years affects that.