So what I read is that the Boxer alignment results in part of the gasket being on the bottom of the engine, so there is always oil sitting on it, gravity pulling it down, and eventually a little bit is bound to seep through.
I think this kind of experience is more typical than blowing out your head gasket.
The thing about switching to another vehicle type to avoid this is that while there are many alternatives to the Forester or Outback that are almost as good offroad, I was thinking of downsizing to a Crosstrek, and it has far less competition, and that which is there is a lot less capable. Subarus keep getting bigger, the current Forester is a LOT bigger than they were 20 years ago and bigger than they were five years ago. And I don't need a bigger car.
Also, regarding getting by with 2WD, for most cases, this just requires going for it and maybe getting a few more scratches. It might mean you need to get some momentum. I once saw a road test where a magazine tried to take a 2WD truck on a 4WD course. They made it, but with a lot more dents and scrapes. Of course in other cases, it means going slower.