hm, it makes sense that you might have to notch the frame. how strong was the frame after you did that?
lately every time I look at the king hauler I keep seeing it with a single rear axle with a set of lake pipes instead of the tandems.
edit: I was looking at your build and noticed you had mounted the leafspring oto the top screw. I put mine on the bottom and decided to see how low it would be if I mounted it on the top.

at the moment all I have thats low-profile are the trailer super singles.