Run a trip as an event
Creating an event before the trip, bringing in the people coming, filing spending against it, and putting it away afterwards.
Create the event
Events live under Events. Creating one asks for a name, an emoji if you want one, and a description. There are no dates to fill in. An event's start is read off the earliest spending filed against it, so a brand new event has no start at all.
Make it before the trip rather than after. It has to exist for spending to be pointed at it while it is happening, and reconstructing a fortnight of receipts afterwards is exactly the work you were trying to avoid.
Add the people coming
Open the event, choose Edit Event, then the Ownership tab, and use Add User under Members.
Only someone who has already accepted a connection with you can be picked, so send that first if you have not. They join with their invitation pending, and can accept or turn it down from their own events list or from the event's page.
While it is running
An event is attached to the expense rather than to the payment as a whole. In the add-transaction form the picker sits under Show more options; on a transaction you already have, it is inside the expense you are editing.
So a meal on the trip is still Eating out: the event sits alongside the category rather than replacing it, and the spending stays in your ordinary breakdowns as well as the event's. Everyone in the event sees everything filed against it, and the event's Statistics tab totals it up with a breakdown by category and a spend-per-day chart. What it will not tell you is who paid for which row.
Handing it over
The owner can pass the event to somebody else from the same Ownership tab: choose them under Transfer Ownership and confirm. You become an ordinary member and they take the owner's controls.
Anyone you have invited can be picked, including someone whose invitation is still pending.
Closing it
When the trip is over, open Edit Event and go to the Archive/Delete tab, which sits alongside Edit Event and Ownership rather than inside either. You are asked to type the word archive to confirm, which is the only friction in it.
The event then drops off your list and out of your event pickers, while the spending keeps its amounts, categories and budgets and the event's own pages still open. Restoring it is two steps rather than one: Restore, then confirming in the dialog that opens. There is nothing to type that time.