If you do choose the “go to costa rica” and get stamped in/out route, you dont have to spend days in Costa Rica. Technically, the law says you have to leave for 72 hours, but every time i have done it i have just always been very nice and friendly and asked if i could just turn around and go back, and every time i can just turn around and go back to Nicaragua the same day. Except one time they made me stay overnight, so i took a buz to La Cruz, staying in a hostel with an amazing view of the Bahia, and came back in the morning. Overall, a very short trip.
I still go with clothes, etc in a backpack just in case they make me stay a full 3 days, but so far, for years they havent enforced that at all.