Max. trailable beam
I think that rather than trying to "make" a trailer for your boat, you would have better luck calling some boat dealers and seeing if they knew of someone who either has a trailer that will fit your Cal 25 or knows someone who does. You may want to look over in the Houston area...tons of sailboats over there.
Check JSI/Sailnets member areas - see if there is a Cal owners email list and go looking for a trailer there or a lead on one.
Just a couple of thoughts....