A couple more thoughts.

Try to be aware of the waves. Start the tack over the top of one and into the next trough as you go head-to-wind, then as you hit the next wave, the idea would be to have that wave peak help knock you over onto the next tack.

One other thing on backing... you may be able to save a reverse capsize by controlling the rudders better too. Hold them reversed, but if the boat begins to back rapidly, you can "trip" over fully turned rudders. Try to steer the boat in a slower backwards arch. Hard to keep the rudders from going full over, but by pinning the tiller to the deck hard, you can hold the rudders from turning too hard.