Just one suggestion if I may. I feel that the hardest part of static training is to find motivation to keep training once you get stuck. To get around that you must change things around to keep things interesting. If you train and train, but are stuck at the same time for weeks, then it's time to try something else. Continuosly experiment and try to find what works and what doesn't. Don't get stuck on doing some tables for months just because some told you it worked for them. Try them for a while, and then switch to something else once the benefit from that training method has been depleted.
For example, if your "pleasant phase" is always 2 minutes and it's not getting any better, then try this:
Don't time the pleasant phase. Start your timer when you start to feel uncomfortable. Try to maximize the time you can bear the "nasty" part. Don't time your total static, just the last part and try to increase the duration of that. Do this for say, a couple of weeks, then try normal way again.
With all the tips and tricks in the world you might get some progress, but in my (and others') experience there's no substitute for simply doing tons of max statics as a training tool.
Also, from my experience, if you think that as times get longer, your statics get easier, you're wrong. In the beginning, yes, the "pleasant phase" get's a bit longer, but that's mostly due to finding the right warmup and preparation. Eventually, real progress is made in the nasty phase. So you must be prepared to deal with a increasing amount of discomfort. The good news is that training helps in doing so, but it does not make the last minutes any more pleasant.
And of course, always remember. NEVER alone in the water.