englishal's examples are all OK under the cost sharing rule, which only applies to payments by passengers. They might be a problem under some other rule, but I can't face looking at the ANO again.
Oh, and mmflynn spotted my error - had to re-read the ANO to see why, and I was working on the basis that the rule prevented a passenger paying more than his/her proportionate share, whereas in fact it means that the pilot must pay not less than the pilot's proportionate share. The perils of posting after dinner, but it reinforces my point about the impenetrability of the damn thing!
If the relevant part of the ANO read something like:
(1) The pilot must pay no less than his proportionate share of the costs.
(2) The planned details of the flight may only be advertised to the members of a bona fide flying club.
then this whole thread would be unnecessary.