Be careful... the boat may actually be longer than 20'7" (specs from MC page) when on the trailer. Most swing tongues do not swing all the way under the boat... they still stick out some.
I bet the X-1 is actually more than 21' on the trailer. Check out this pic. You can see that the tongue is swung back and yet it's still apox. 6" beyond the bow of the boat.
The only way to know for sure is to measure one yourself at the local MC dealer. Bring your own tape measure.