As noted, so long as you have zero-loss connection, fragmentation is not an issue. For example, my HE.NET connection is a corporate one and out of the peak times (around 3 p.m. work days) it passes all tests for any MTU <= 1472 and MSS <= MTU - 20. Problems arise only under heavy load.
By the way, the harder targets (to me) are those in Eastern Europe, Latin America, and Africa.