The hardest part is doing it safely which requires space and tools some people don't have. However if you're of a mechanical mind and think about things carefully it just requires work.
I've got a thread detailing how I did my L175
here. It covers the clutch, reverse gear, removal of the head, and reassembly of the halves. Eventually it will cover a full cylinder and bottom end job plus full reassembly but that's in the making.
There are a hundred different ways to support the ends but from doing this I can tell you the front end is the hardest. The rear can be done fairly easy like I did up there. It was mobile, stable and relatively easy to move. The trick is to judge your weights and leverage correctly so it doesn't tip over easily. The front wanted to rotate on the center pivot for the front axle when set down on the jack stand. To fix that I had to support the front bumper with jack stands and then place a jack stand in front of the oil pan as seen at the end of post #15. I couldn't go behind it because what was behind it was the part I had to remove (the starter casting). The problem was that gave it enough leverage that it wanted to tip easily so I filled a 5 gallon bucket with water and set it the battery pan. Not the greatest idea but it worked.
Hope that gives you an idea of what you're looking at.