If you have tools and a decent amount of woodworking skill, you could build a SICK mailbox rail. If you cut the pipe in half the long ways you'll get a rail twice as long, that bump-up on the end would also need to be cut out. To mount it you could build a flat box frame the same width as the bottom of the cut in half pipe, and then to attach the pipe you could custom cut a 2x6 or 2x8 (maybe you'll get lucky and no custom cutting would be necessary) to fit perfectly inside the widest part of the cut in half pipe. Then attach the 2xwhatever centered on the top of the box frame. The pipe should then lay on top of the box frame with the custom cut 2xwhatever sitting inside of it. Then pre-drill holes and screw in from the sides of the pipe into the fitted 2xwhatever. If done right it should be very sturdy. This will take a decent amount of work but will leave you with a very nice mailbox rail, very long and very sturdy. If you're interested in building it this way and have any questions feel free to ask.