The chord from leading edge to the trailing edge fillet on the wings
are typically longer on standard class ships. i.e. the height of the
clamshell can be higher at the spar end for standard class trailers vs
15M trailers of the same era.

We had a pilot borrow a 15M trailer to retrieve a standard class ship
.... everything seemed fine ... they closed the top and didn't feel any
resistance ... but then noticed two 'horns' sticking through the top of
the clamshell at the front ... i.e. the trailing edge wing fillets of
the wider std class wing had pushed through the glass top of the 15M
trailer.

You can measure ... but if tolerances are close ... put the wings in
and have your partner close the top slowly as you check the distance
from the wing root TE to the top of the trailer. Depending on how safe
you want to be, and how close your measureed tolerances are, you can do
this in the trailer with a flashlight. Also, newer trailers have spar
hold-downs that may have to be adjusted ... the older models have holds
downs that kinda grab the wing root ... not as good to prevent bouncing
.... and maybe more of a pain to adjust for different gliders.

KK