typical setup for chargebacks or subsidies for an organization like this is you charge based on '% of use' out of the possible rather then actual consumption. The costs become operational costs that the facility must budget for in their total revenue. It's never a 'per guest' fee, just like you don't try to figure out 'how much of my room fee is for laundry of my bed sheets'. It's a pooled cost that the property must offset with revenues.
Simple example... say ops agrees resorts should fund 50% of transportation's budget and they come up with a number.. pick an example #.. $20mil. Then resorts goes and says 'well we gotta fund $20mil, and the prime users of that service are these three properties.. and since GF is larger, we are going to say they own 40%, and Poly and CF owe 30% each'... and that number gets added to the operational expense of each resort they must offset with revenues.
At the end of the day... it's an expense the resorts must cover to help subsidize the larger operation. Where the divides are is accounting magic, that often has much more to do with accounting manipulation then it does with any 'per guest' type of modeling.
For instance, it may be more desirable for one operation to run with higher costs due to tax reasons... so you make that operation 'pay' for the services of another... reducing their profit and shifting revenue to another group that may have more attractive balence sheet or tax implications.
In short.. you all are chasing #s that probably have little actual connection to how the business operates.
Yes you can say 'the resort owes $5mil, and they have 500 rooms, divided by 365 days', etc... but it's an artificial number that really doesn't correlate to actual prices. Prices don't move with costs... pricing is set to have target margins above costs, and other factors keep pricing isolated from true costs too. Pricing is all 'artificial' as long as the total P&L unit number is at it's margin targets.