Overlaps, Equipment and Zone

It obviously depends on the speeds you're doing and the length of your spinnaker pole. In planing conditions it would be hard to argue that you broke the overlap with the boat behind because they retracted their pole anywhere between 2-4 boat lengths of the mark. While in lighter stuff there is no reason you can't leave the kite up well inside the 3 length zone. If you're giving mark room to other people at the same time then this all goes out the window. At the 200 nationals you can be dropping your kite 5 lengths from the zone to slow your self down as you let everyone clear ahead round.  

If I was overlapped inside and pulling my pole in would break the overlap I would shout loudly that I'm overlapped and just send it as late as possible into the mark so there is no doubt. If I was unsure if I was overlapped or not I would just tuck in behind. A lot of mark rounding has to do with who you're near as well, picking your battles based on who will be hard but fair and who will just outright not let you past even if it was clear as day you were overlapped is a big part to it too.