What’s the fairest and most practical solution for managing drink costs on boys weekend away where people drink different amounts?

I’m going away with 8 male friends on a golf/boys weekend where we will have a couple of nights out which are likely to involve pub crawls.

Different members of the group have different financial situations and they also drink very different amounts. Some may have 3-4 pints and others may have 10-12.

I’m trying to work out what is the easiest and fairest system for buying the drinks that means that those who don’t drink much don’t subsidise the big drinkers but also one that doesn’t mean everyone just buys their own drinks.

Any suggestions?