I have the same problem. Because I can see the instrument panel just fine with my distance correction glasses, my bifocals have just a tiny D-shaped bit at the bottom for reading the map. this means the line between the two sections doesn't get in the way at all; I found it did with any other way of setting it up. If you can, find an optician who's used to dealing with pilots - maybe ask your AME - and experiment a bit to find out what works best for you.