Soldering iron is a great idea we bought it for wiring and used it as a hot knife for the carpet. We bought 5 x 2.5 way to much for my wagon and a heap of glue and underlay also helps with the awkward shape of the floor. And we did it and sections from firewall to the frame where seat mounts on then from there back and cut stuff out with the soldering iron or stanley knif as you go like seat mounts some edges and what not. We at the very start cut a strip of it we knew would fit cut out around gear stick and handbrake was getting worried at first but when we finished was very impressed.
Our carpet was not flexible or maluable so in corners pushed it along both edges flush till you get a fold of excess and then we cut it and fiddle till it was flush. The carpet meats up very well ant even see its not one piece
