I can think of a couple of things working against you:

1) Commercial dowel stock is almost certainly kiln dried wood, rather than green wood, so whether or not you're steaming your wood, it's not optimal for bending.

2) I've never heard of anyone bending round stock, except for ribs in a baidarka, and there they often use whole branches with the bark stripped off. The problem is, when you bend round stock, the maximum stresses occur in the areas of minimum material.

Mike Scarborough
Friendship Kayak