Bill, No one can tell you what to do. You will have to make up your own mind. Most people pass the tests, but if your doctor is telling you that you will be over the limit pretty much no matter what, then ?.
I would say come down, take the risk, do a great job and if you npq then come back again next year at winfly. 4 months on 8 months off year after year is hard, but 6 on6 off with unemployment isn’t too bad. You go back to the states for the summer and pick up summer jobs before you return. Just make sure you do good enough here that they are dying to get you back.
There are a fair number of people that work in the National Park system when they aren’t working here. Sort of the best of both worlds. Take the risk and let your life go where it may.