Ipe is some crazy heavy/hard wood. Friend of mine sent me some offcuts a few years ago and I honestly had a hard time working with it(I was hand making pistol grips at the time). I ended up giving it to another friend, who in return gave me one single ball point pen he turned on his wood lathe. Yes, big box of walnut, maple and Ipe offcuts traded for a single pen, a very nice pen, haha!!! I would suspect if you can get a big piece like an XXL waste board Ipe would make a very solid bed.
I've tried to cut through many projects without cutting the waste board. Current setup is an 18x24" HDPE cutting board that I threaded and trammed flat. What I usually do is set my Z zero on the cutting board, with a thin piece of paper between the tool and the board. Then I jog up by the material thickness and reset Z zero. The results haven't been too bad, but works best with small parts where I've used 2-sided tape for work holding. I'm currently planning a totally different waste board setup, but this idea should transfer over pretty well think.
I honestly haven't had time to get back to my bed flatness musings. I've been working on the new house and preparing for "The Move" which is slated for this coming Friday. Add to that some sort of ugly cold/sinus infection this past week or so and all I've managed to do is go to work and sleep for the most part. I hope to get back to this very soon!!!
Oh yea, I finally got a shed installed last week to house those pesky "garage" things that tend to muck up my workshop space!