Hybrid composites also resists crack propagation. Which I would also group with fatigue. The Gougeon Bro's book on wood boat building mentioned Kevlar added to a carbon layup would resist crack propagation. You can email DuPont and ask for more information. In the past they have been quite helpful. (Be sure to ask for composite layup information on all of their products) My carbon beams have 1 layer Kevlar for each 6 layers carbon. It was the Kevlar that held the beams together long enough to get to shore when the carbon failed.

Concerning your board failure issues, research resins. Epoxy resins may not all be equal. Resin suppliers will usually give you fatigue info.

In my opinion you have a right to be concerned about fatigue. It is rarely mentioned. Builders of commercial items will provide fatigue information if asked. Consumer product builders fall back on "We offer a lifetime or 20 year or ? warranty" which leads me to believe they expect you to sell or trash whatever they sold you before fatigue becomes a factor. I suspect one reason is if you had that information and repeatably used a product near it's limits and it wore out early, you could force them to replace it under warranty. Currently it is common for companies to refuse on the grounds that you abused their product.