Today, if you buy a villa it will be in the neighborhood of $1 million US. Your $300,000 deposit would earn, conservatively, 5% invested anywhere else.
Can you give more details on that conservative 5% please? You won't get more than 2.5% in Australia or the UK if it is a bank deposit and personally I would consider the stock market to be way too volatile to be relied on.
In my last job we flew 80% pax and 20% freighters, don't think I ever did a single freighter roster that wasn't changed down route. Trying to plan commuting, without the full support of rostering, would be a very stressful, (possibly heart stopping), exercise, I would think.