Well - I have to say that cohabitation in general is risky business. We've had considerable experience in that over the years and this is the conclusion we've come to.
If you think about the "issues" that crop up with just 2 people living together and multiply that exponentially (because that's how it works) you'll understand. It's an adjustment in our daily lives, we have to make some compromises to our "comfort" levels, and those niggling little compromises can lay dormant under the surface and fester until something else comes along and they become a full blow outbreak.
The solution we've found - along with thousands of experienced others - is to only consider it if you can guarantee there is sufficient "personal" space that can be afforded everyone. This means separate bedrooms, living space, baths and even minimal kitchen capabilities.
You will find these models working in many intentional communities where polyamory may or may not play a part. The concerns are the same, only polyamory adds additional complications- or emphasis.
In addition, I think it's important to find ways to as completely separate the bureaucratic elements from any "relationship" element as much as possible. Things like financial agreements, responsibilities, schedules etc. Treat them as much as possible as elements that stand alone, with their own - non-relationship discussions and try to avoid crossing boundaries as much as possible.
It's a tricky social dynamic and the last thing anyone wants is to have day-to-day concerns bleed over into the relationship side.
I'd recommend maybe taking some time to read up and talk with people involved and experienced in the "intentional community" community. There's much wisdom there that would probably be helpful.