Who pays for the groom?
On many bachelor trips, the group covers the groom's share of the shared costs. It's a tradition, not a rule, so the group decides. His own travel and anything he buys just for himself usually stay his.
Put it in the first message with the budget, so everyone knows what they're signing up for before they book flights.
Split shared costs evenly, extras by who goes
The house and group dinners usually split among everyone. Optional extras, like a round of golf or a show not everyone goes to, split only among the people who go. In a tab, each expense can be split among everyone or just the people it was for.
Collect for the house before the trip
Whoever books the house is out of pocket from the day they pay. Turn the calculator into a tab and the house goes in with each person's share, and the tab asks everyone for it right away instead of after the weekend.
If someone is only coming for one night, split the house by nights instead, so they pay for the night they stay.
Keep the rest of the weekend on the same tab
Dinners, rounds, tee times and rides: add them as they happen and let the tab work out who owes whom at the end. It boils everything down to a short list of payments, so nobody sends money in circles.
GroupTab keeps everyone's Venmo and Cash App in the tab, so paying is one tap with the amount already filled in, and both sides confirm when it arrives.