Do not have the 230 or 235 but have a Fenix 3 HR. I use vibrations on almost all my workouts and usually have no problem with them, even in the pool. Occasionaly I will miss one though.
AFAIK, to do the type of customization you want, youll have to create a workout in Garmin Connect and load it over to your watch, then start the workout there. I do this s ometimes. It works reasonably well but it can be a hassle. There are a limited number of factors you can "track" at a given time during a workout too. For example, you cannot set a workout to run 10 mins while vibrating if hr tracks outside a custom zone AND vibrate if cadence tracks outside a custom zone. You can do one or the other but not both, of the latter. But, if you're doing a LSD run and want to keep your HR in Zone 2 but cadence high, you can set the watch's custom alerts on both of those items right on the watch rather than on a custom workout, and it will work fine.
But again, that's all on the Fenix 3 HR. I assume forerunner is the same but can't say for certain.
Also, highly recommend a chest strap if you want high quality HR data. if you're just in for fun, the optical works fine.