Forget trying to reflex the limbs with steam - it will pull out.
If you have a heat gun you can heat treat it either once, once finished or both. Don't try to induce much reflex just try to make it straight or upto an inch of reflex.
Heat treating is simply heating the limbs until they are a medium brown (not black). This process will get rid of the excess moisture and increase the bellies resistance to compression.
Hickory is so strong in tension that it overpowers the bellies ability to resist the compression - think of an unbalanced seesaw with one fat kid and one skinny one. When bow making we want the kids to balance
the way around this is trapping. Trapping is reducing the width of either the belly or the back (most cases).
Reduce the width of the back by 1/4, an 1/8th off each edge.