Combined road/trail movement

[J6A]

So, foot units that do their entire movement on a trail get +1 MP. What about a unit that starts on a road, and then ends on a trail?  In the picture below, 2 cavalry stacks (5 MP) started in 0409 and 0510.  The one in 0510 moves along the trail and so can move 6 hexes.  However, in the RAW, the one in 0409 moves to 0510 for 2/3 MP, then can only move 4 more trail hexes, expending 4 2/3 MP.  Essentially, it's penalized by starting on a road instead of a trail.  Should a road count as a trail for purposes of getting the bonus MP?