Duncan,
my advice would be to go for it - if you can - but it is a ton of work, and every waking spare minute will have you thinking about it. At the top of your list should be the two most important things from my experience.
1. Whatever you do, do it the best you can afford and have time for - if that means a 40-80 yard short game area only - that will be just fine, as this is the element that improves your game, and kids etc love it. Consider your budget and don't stretch it just so you can have 180 yard shot, the extra is not worth it!
2. Probably supersedes number 1 - make ALL your plans with maintenance foremost in your mind - you must be a practical guy building & selling furniture, same principles apply, cost it as though you want to make a profitable piece of furniture, if the numbers don't add up, don't do it, there is nothing sadder than looking out your window (everyday) at a poorly maintained golf landscape, because a) you haven't had time to maintain it b) don't want to pay someone to look after it for you OR c) you didn't think it through at the design stage.
I have a mate of mine who is half way thru his own, he now says he wished he had bought my place, as he cannot believe the amount of work and cost.