@Michael Daubenspeck Sea Ray didn't carry trailers at that size; have you checked with your local dealer for a referral to a reputable trailer company in your area? If not, I'd recommend starting there. Good luck in your search!
I have a trailer that fits my 2001 310. The entire rig with truck and trailer, empty water, less than 1/4 fuel but with lots of gear weighed more than I expected at about 26.5k. You'll likely max out an 18k trailer as 8.5k of the above was my truck. we have to remove the radar to not be over height but thankfull can leave the arch up. It wasn't cheap and if we sell the boat we'll sell the trailer separately. For used trailers check the hull truth site. Good luck.
I just had one made to fit my "97" 330da (in joint venture with a friend fit his 87 410 also), so its a little long for mine but adaptable, through- Fastload Aluminum Trailers in Plant City Florida, 813-737-9884. trailer weights 1480lbs cost 7,295.00 delivered, now remember that it is a bit larger than what i needed so it cost just a bit more. Just tell them what you got, can send pic of bottom if you have it and they will make it the way you want it. Hope this helps.