I have both the Map DLC and LH- they are not compatible. Steam also doesn't list any DLC for LH. Given the additional content added in LH, and the hand-crafted nature of the DLC maps, I doubt they could be made compatible without work. In short, at this time, there doesn't appear to be any point in buying the map pack if you are playing LH.
If someone makes a huge "Wildlands" style map for LH though, I'd definitely try it out. 
