I've never had much luck gluing a backing on ipe because it was so oily, but if you can clean it first really well with acetone, it should be fine. I made a hickory backed ipe once, and I treated the dimensions just like I would a solid hickory bow, and it came out a bit stronger, so you can start your dimensions out somewhat narrower. Maybe by 1/4" to 1/2" narrower, this stuff is tough!
My hickory backed ipe bow exploded in the house when I was attempting to string it to show it off to my wife - it was so loud that the dog peed in two rooms at once! So, be warned, get your ipe CLEAN before you glue!