Hey Mike, it touching the bottom is a problem because it's going to try and wear a hole through the bladder. I think the ring on the end is to try and make a washer and spread that versus the tube having a wad punch effect. I think we discussed these already and because of their position and height they will read full until about 1/3 of a tank then drop quickly to empty from there. I cut the outer tube with a tube cutter and the inner with wire cutters, it makes it a lot cleaner. You could do that to get a tad more clearance on the end or deburr that one and straighten it out some. Once you have the tube trimmed to length calibrate it to the gauge with it out of the car. Instructions are here or call me to talk you through it.
http://www.centroidproducts.com/pic-cal-3-15-2011.pdf