Good point. If you want to do this, you want the 'U' shaped version. If I remember correctly, it cost me $8.95 for 25' at Pep Boys about 3 years ago. The only place I had trouble with was at the rear and front of the tank where the bends are more radical.
Three things I will do when I get around to re-doing this. One, clean the crap out of all edges. I thought I did a good job on this (see above). Two, get one of those wallpaper seam rollers. The glue in the bottom of the 'U' is pressure activated and one of these tools or something similar, would really get it on good. I took me a bit last time to make it look good. Three, I'd blue tape the fronts and backs until the glue set up good. Neither end is noticable to anyone but me but hey:
Any job, big or small, do it right or not at all.
