John,
I actually had some problems with white oak backing on a similar design.
Thats one of the reasons I've been moving towards the R/D profile. It helps to reduce surface tension on the backing and surface compression on the backing. Should make the bow a bit safer at a given width, length, and draw weight.
I'll get the pics up soon of one like yours I just finished, I went 60" long and 1.75" wide for a draw of only 25" and 45#.
I figure the few FPS I'd lose going wider is well worth the gain in safety. Since a wider bow takes less set, it's probably almost a wash in terms of speed.