OK,
You seem pretty balanced in your SBR abilities right now, but not exceptional in anything. I would guess that you have no real competitive background in any of the 3 sports and you have been doing tris for several years before your layoff last year. Am I right that the 22:30 1500 and the 40min 10k were from a wetsuit legal triathlon? That would line up with your other stated pb’s. Also, if you did the 24.4mph at St. Anthony’s, what wave were you in? When I did that race I was in wave 20 and enjoyed a continuous 40km of slingshot drafting. You may get some legal benefits at Disney, but they won’t be that good.
Bottom line is that 4:20 is a tall order. You could go 4:20 at the Esprit, but that’s a different race.
However, this doesn’t mean you shouldn’t train your ass off. 4:20 at that race in 2010 is much more realistic. Most people overestimate what they can do in the current season and underestimate what they can do in 2-5 years. The danger of setting stretch goals in the short term is the discouragement that can come when you don’t hit your times and the possible drop in motivation.
Keeping in mind that I don’t know you, I suggest you consider setting a run goal for Florida. Breaking 90min on that run sounds like a very challenging but achievable goal for you that requires deep fitness in both the bike and run. You will also have to pace your ride to do it, which makes the likelihood of a positive first Half IM after your layoff much greater. Chasing a stellar time by going hard on the bike is a risky strategy, especially on that course.
My 2c