Here's another angle to consider. You say that your goal is to reduce set, but I believe the truth is you're trying to reduce string follow. They CAN be manifest as the same thing, but they're two different occurrences. Let's assume you start with a dead-flat board bow and end up, after tillering and shooting in, a bow that follows the string by 2". Thus, you have two inches of set and two inches of string follow (in this case, manifest as the same thing). However, if you heat 2" of reflex into the board, and then after tillering and shooting it in arrive at a dead-flat profile, you still have 2" of set but zero string follow. Like was mentioned about, set happens. Even glass bows will take a touch of set, even if in the most minute amount. You're straining material in both compression and tension, and something must settle.
Here's a red oak board bow I made for a friend. I heated 2" of reflex in and arrived at a flat unstrung profile immediately after unstringing and just a touch of reflex after settling back. So, to the original question, yes you can achieve a dead-flat profile on a red oak board bow. But NO, you can't avoid set.