If you want your Easton poles to take anything tighter than about a 2m radius of curvature, you must give them a pre-bend. In fact the limit for the 344 tubing is about 1m or 40" radius of curvature, but this is pushing the material too far.
Translation: I pushed a set of Easton 7178-T9 poles in my orange tent too far, and they ended up shattering in the Pyrenees near the end of the trip. Oops!
However, do not prebend the poles to the full curvature you want: that way lies failure as well. Only go about half way, so that when the tent is erected there is still some tension in the poles. Um - the exact details may vary, depending on exactly what final curvature you want.
Now, how to curve the poles? Yes, a board cut to the shape you want is not a bad idea, but the problem is how to roll the tube down onto it. This is not so simple, especially when you want a parabola rather than a circle.
The alternative is a tubing roller, like a 'Jenny'. You will need to look this up on Google to see what it is. The idea with one of these is to make several passes along the tube, increasing the amount of curvature each time. But you need to use rollers carefully shaped to fit the tube or it will buckle. Again, a bit complex.