I have always used the ply plate + dowel method referenced above, but I put RTV (silicone) into the holes in the foam core for the dowels. That way, if there is some flexing in the ply plate the dowels won't widen the holes in the foam. The RTV acts a bit like a shock absorber. I fly off of grass and this has worked well for 2 Deceptions, 1 Tipo, 1 Escape, and 1 Pursuit 120. The gear will bend before the plate pulls out. In fact, with the Rhom gear legs I have to periodically rebend them slightly.