Others have suggested applying lanotec or chain oil, both of which may stick around for a bit longer than RP7. There was also a member who achieved some success by bending the verticals on his u-bolts outwards from memory.
I have aftermarket springs on mine. When I got a squeak it was resolved with a lump hammer by realigning the leaf pack away from the u-bolts a bit. The squeak hasn't returned as yet.
I think it may be the spring clamps which you are referring to. These are U shaped brackets which help align the leaves. If they rub against it, you will get a squeaking noise. Bending the clips back or realigning the leaves will help reduce the squeak. Leaf springs themselves are designed to work on friction so you will get squeaking no matter what you do. Regular servicing is recommended on any leaf pack to keep them working properly and will prevent excessive squeaking.
Have a look at this video of the rear suspension on a Triton working on normal road conditions. You can see how much the springs actually move and can appreciate why you would get a squeak under certain conditions.
http://www.youtube.com/watch?v=_o8mHmDfet4The is Fraz's vehicle which has one of our 2" lifts and the video was filmed when a set of the firestone airbags were fitted. They have since been removed because he doesn't require them but it gives an idea of everything works in together