Here's the height of a 10w Soft White 2700k LED in a cleat socket
If you run your CFLs horizontally like I did in these tests, you probably aren't going to have them touching the edge or ceiling of your cab, so there will be some space around the bulb. The height of the 10W LED is about the same as the width of a CFL bulb plus a little space around the bulb. IE, you probably won't gain or lose space by swapping out the 10w LED for a horizontal CFL.
If you hang your CFLs down, then these LEDs will save you space.
Here's a 14w Daylight CFL hanging down next to a 10w Daylight LED with its lens removed.
Here's a 13w Soft White 2700k CFL next to the first two Soft White 2700k LEDs I posted in this thread.
Here's a 23w Soft White 2700k CFL next to the first two 10w Soft White 2700k LEDs
Here's the 40w Soft White 2700k CFL next to the two 10w Soft White 2700k LEDs