I don't think you really need to worry too much about mast bend. I have a halyard on my TI mast so I can deploy a masthead light, so I can easily see how much the mast bends compared to the halyard (which is tensioned by elastic cord). Normal sailing to windward sees the mast bend about 10cm measured in the middle. Bend increases some as winds pick up, but then the bend begins to automatically spill wind from the leech of the sail. As you reef, the rolled sail strengthens the mast, but the bend still exhausts excess wind pressure on the sail..
I think the forces are under control overall.
2012 Tandem Island "SIC EM" with Hobie spinnaker!