I'm saving up my money in career mode, but I'm wondering if I should spend it on upgrades. My main question is: will I miss out on certain side missions if I buy certain upgrades late in the game? By this, I mean; will I, for example, miss out on some/most of the search and rescue missions if I don't get the winch early on? Or will all these missions still be available to me late in the game, as soon as I buy the winch?
Edit: I just got the first government mission and completed it. I can now see that there are other missions available which require a winch, etc. Is this how I get all side missions - they show up as I complete the story, rather than when I buy upgrades?