[MrForbes]

Originally Posted by The Lucas

I wasn't going for practicality, I was kidding about building giant Motor Trend Car of the Year style outside calipers.

You may have been kidding, but it might be helpful to make your own giant outside calipers, set at 80", from whatever is handy...say an 8 foot long by 4" wide strip of plywood and two shorter strips screwed onto the ends at right angles, with exactly 80" open space between them. Then you can check yourself to see if there is any place around your robot that you can't fit within the 80" limit.