Looks like temperatures are staying above 0C in the region, similar to England in recent weeks. I've heard that snow has melted in Lithuania, but expect the ground to still be wet and covered in last years' fallen leaves (which had plenty of time to rot too, yuck).
LT: Generally speaking wild camping next to lakes is the way to go. Country guest houses are plenty in the summer, not sure about this time of year. Keywords: rural tourism, kaimo turizmas.
Just found out mosquito forecast is a thing lol. You should be good now. Anyone attempting this in summer beware!