movable bases

[greymule]

I umpire a modified pitch league one day a week, and on every field we have to deal with light, bargain-priced bases that are never spiked down. (The league says they're not allowed to spike them or put in permanent bases.) Naturally, these bases move every time somebody slides into them and often even when a runner steps on one on his way past. Last year, the umpires made their calls according to different criteria, so this year I'm codifying the rules for uniform application.

I would like to give the following plays as examples. How do you think they should be called?

1. Runner slides into 3B. The base moves 2 feet across the line, and the runner ends up another 2 feet past the base and is tagged.

2. Runner slides into 3B and knocks the base 15 feet away. The runner ends up past where the base originally lay and is tagged.

3. Runner slides into 3B and knocks it into the coach's box. Runner goes over and stands on the base and is tagged.

4. Runner slides into 3B and knocks it a few inches across the line. Runner is tagged standing on the base.

5. Runner slides into 3B and hooks the base with his foot. Both runner and base skid 6 feet across the line, with the runner still in contact when he is tagged.

6. Runner slides into 3B and hooks the base with his foot. Both runner and base skid 6 feet across the line, but the runner loses contact and is tagged.

7. R1 on 1B and B1 hits a double. As R1 passes 2B, he inadvertently knocks it 6 feet toward center field. B1 stands on the base and is tagged.

8. Same play, but B1 stands on the spot where the base originally lay when he is tagged.

9. Runner rounds 2B and dislodges the base 3 feet. He then dives back into 2B, but when he is tagged, he is clearly not where the base originally lay.

10. As F6 covers 2B on hit to the outfield, he knocks the base 3 feet toward right field. On a close play, the runner slides into the moved base as F6 is making the play where the base originally lay.

Can anyone think of other variations we should cover? I would like to give them a general rule to follow, but coming up with one isn't so easy. I appreciate your help.