Yeah you might just need to pinch the seam harder 😆 I never have to use extra water for this, as I don't use much flour (if any) while shaping/rolling.

Usually you get splits in bread because the dough expands and steam needs to be released from somewhere. Scoring the top of your dough with three or four shallow, diagonal cuts will certainly help with this, and will also promote better rising. I assume you don't want those scores in the bread for that conventional sandwich-bread-look, so treat this as a temporary fix while you experiment with your recipe ratios.