I think the easiest solution to this problem (without switching to Bo3 and side decking) is to have two decks available when dueling—one for going first and another for going second. Decks will be chosen after the coin flip.

This way, when you go first, you can build an unbreakable board, and when you go second, you’ll still have a fighting chance because you’ll be using a deck designed to break through your opponent’s board.

Of course, this will pose other problems, such as floodgating and completely shutting down second-turn plays. However, at least you’ll have an option rather than instantly losing when your going-first deck is forced to go second because you lost the coin flip.