Edit: Yeah, that sucks. I generally try and check my map allowance before I go fishing if not, I deal with the crappy map. Not sure the below helps at all.
There are certain fishing holes that only give certain maps. So that's your best bet. Want Peisteskin maps? Mor Dhona over near where the hapalits are. There is a boarskin and toadskin hole as well in MD. One is the swamp area and the other is near the plasmoids, though I don't remember which is which.