the mounting bracket is just 2 stainless screws screwed in the bottom of the boat. It's not even needed with a manual pump. It doesn't care if it right side up, sideways or upside down. Buy new pump from walmart for $20, undo hose from old pump, put same color wires to same color wires, put hose on new pump, drop back in bilge. Who cares about screwing it down, it's not going anywhere.
Dude, it's the easiest thing you could do on a boat aside from changing the anchor light bulb. If you insist of not doing it, I'm sure there's plenty of people in your marina that would do it for a case of beer. 2 screws, one clamp, 2 wires, 1 screw driver.
Really.
If you want a cheap upgrade, get a 800gph pump. They share the same hose size as a 500
http://www.walmart.com/ip/Tsunami-800-G ... C/11071214