Totally doable. But whether or not it's "crazy" depends on all sort of factors you haven't mentioned...

• What kind of terrain would you be building on?

• What's your time deadline for finishing?

• How many people will be working on it and how much time do they have to spend each day / week?

*What KIND of fence....[do you have plans; do you know what you're going to build and know how to do it?]

• How experienced are you at building fences... or at building anything.... Is this your first project?

• Do you have experienced people to call on for help if you need it?

It could be a complex undertaking or an enjoyable experience.

I spent five years building a wooden fence around my property.