Refs should be allowed to call "no interference" when players are trying to milk a penalty. Upon hearing this call the tacklers are then allowed to dive or flop back onto the prone player while the ref adds another tackle to the count.

IIRC the wording in the laws is something like "the tackled player shall immediately regain his feet..", so there's scope to penalise a player who fails to do so.

There's also the section on misconduct, which includes "behaving in any way contrary to the true spirit of the game", which could be used to penalise such behaviour.

Any player diving or moving off the mark should have a penalty given against them and im sure it would soon stop if it was consistently enforced. If that team does it a second time in the same game send the player to the bin.

I agree - it would make for a few rounds of messy games, since the practice has become endemic across all clubs, but if the coaches were made aware of it and it was consistently enforced, they'd soon pack it up and find another way to cheat.