Have patience. When the other maps are released they'll all fit together and the cut-offs will be no more.
Of course, at the rate things are going, we don't know when that's going to be. By the time all of them are finished modern computers might not even be able to
run Morrowind anymore.
This is perhaps one of the reasons why I don't actually use any of the Tamriel Rebuilt mods, they would be very nice until you get to the point where the land just... ends, which I think might be a bit too much for my suspension of disbelief.