To remap your model just use the grouping tool by assigning the regions and saving by name 1: Write a new group 2: Mark the polygons best way is to increase your selections by bolygroups with the + after selection 3: Assign Material 4: Delete new group as you will not need it anymore

this way you can assign as many Map regions as you wish .. needs a little training but easy to do after getting used to the group editor