I don't have much experience in this area, but will say, I think IPE should be backed with hickory or bamboo or something.
I got flooring planks from a flooring store. And had to plane off the glue slats I think they are called. Ended up being less than 5/8". Really you want at least 2" thick. That way, you can put on a tablesaw and get a good 3/4" thick piece so it will not bend in the handle much.