I do three splices in mine all the time. I cut them on 45 degree angles on the miter saw, gouge them with the toothing plane, and glue them together with Smooth On... staggering the joints by 1/2" or so.
Butt splicing bamboo shouldn't be a problem.
And yes, ipe would work in a laminated bow. Pretty much any wood that will make a bow without glass will make a bow with it. Though I usually prefer less dense wood in between the glass.