Feel free to amend "my rules" to suit. I've just noticed the document I gave the link to is to the old rules. We amended them earlier this year to simplify them a bit (reduce the amount of admin required) - latest doc is here:
https://lookaside.fbsbx.com/file/COR...pkTGEbBMgMR8gA
As for multi-car events, yes we do sometimes have quite a few cars in play at once - our next one has 6 cars per team, so with our 4 teams, 24 in total, in a fairly small, open arena. We quite often fail to finish a game in a single evening, so simply make notes of the current state of play and stick down vehicles with blue tac (dropped weapon counters get stuck down as soon as they're placed).