Stepping the mast, w/o crane
I suppose it is possible to step the mast with out a crane, but the "stock" design of the boat would make it hard to pivot the mast up using the boom as a "gin-pole". If your boat has been modified, and has a hinged maststep or tabernacle, then with care it should be possible to pivot the mast up or down. To use the boom would mean the mast would need to pivot up from the bow, so the hinge will need to be designed/set-up for this. I based my original answer on the assumption that the boat had the original mast-step design. Even with that original set-up it may still be possible to pivot the mast up/down, but not as easy.If you have a deep (and steep) ramp to launch from, and a long extension on the tongue, it may be possible to ramp launch off your trailer. However, without seeing it, I can't say for sure. You will need a powerfull truck to do this since the boat alone weighs over 5000#, then add in the trailer. The 4' draft of the keel means you will need to get the trailer pretty far out into the water to get the boat off. I admire your spirit, but am just cautioning you from experience that it is never as easy as it looks, but may get easier as you do it often enough. I have observed people trying to launch boats drawing 2' of water being frustrated by needing just 1-2 more inches of depth to get the boat off the trailer, so close and yet so far! I have also read about people ramp launching a Catalina 27 after stepping the mast themselves, wish now I could find that magazine article!