Yes, cut relief lines and they will naturall overlap. Do a dry run first and the material will show you where it wants to be cut.
After you start wetting it out, If you are using a disposable brush, just dab-dab-dab (using the front of the brush) the brushes fibers will mix and meld the seam away.
If possible work with the tank on it's side, not up and down. It uses gravity in your favor and you won't have your head down in the fumes. Use a powerful fan to to keep your work area well, and I mean well ventilated !