Ramps and Fixed Keels
First choice: launch with a public sling hoist.
Second: use a travel lift at a yard.
Third: find a way to use a slopped launch ramp with own vehicle.
If using a ramp, find one with a fairly steep angle - this angle can vary.
Only use it a high or near-high tide -- lower part will have a lot of slick growth on the paved surface.
Then use a trailer designed for this. Easy Loader used to have a model in the late 70's with a tilt arm on each side with their signature roller assembly on top of each tall arm. An extension tongue was still needed, but with the trailer all the way submerged the cable could be eased out and the rear roller assembly would hinge back and downward and (hopefully......) the boat would launch and float without banging the keel on the concrete.
Retrieving was quite entertaining to watch, as well.
(Picture of such a trailer in reply 5 in this thread.
https://forums.sailboatowners.com/i...a-27-and-questions-about-what-trailer.150219/ )
This would work OK if the draft was around 3.5 to 4 feet.
Plus, the trailer would corrode away pretty quickly from the salt water, also.
Not sure without some research... but I believe that these trailers are long off he market.