The point is that 10mins of water also takes a long time to get into the mast, so it must be sealed reasonably well already.

Righting technique will go a long way to preventing a turtle. Get onto the hull as early as possible, bring bow into the wind, then snuff the kite (most systems should enable this from under the tramp), re-right.

With this technique, the only part of the mast that needs to be sealed is from about the spreaders up, with higher priority the higher you go up the mast.