Personal, and somewhat facetious, view: If it becomes standard practice to "deal in" players who take a shift as portrayers, I want a cut as well. Following the logic, I give up an entire weekend and all hope of components, coins, or formal scrolls and only a very limited pick of magic items that a standard portrayer weekend doesn't even begin to cover in terms of required GS. I can easily narrate that my character is, in IBGA-land, wandering around valiantly doing their duty protecting New Acarthia as part of the Ducal Army or somesuch. So can I get dealt in?
What about actual members of the town guard who are not adventurers? Can they get a cut since they were protecting the town—and risking their lives (to great peril, based on the periodic death count of towns guard members)—even though they aren't out in the field helping Her Grace gain the power of the landbond directly? Or for protecting the town while you were in Death's Islands?
Now, I don't actually want that cut, because really: Treasure found on these encounters is an IG construct, not an OOG one. Portrayers don't get a cut for the encounters they aren't in, because their characters are not in those encounters.
I also admittedly find paying people who go on "guard duty" strange as an idea, unless you are already paying people for doing so with their actual physical selves (or in their IBGAs, for that matter). A while ago we had a few people spend their IBGAs trying to find ways to kill necromantic cats that were causing problems for the livestock, yet I don't think any of them were actually paid by any adventurers for their efforts. In my mind it just creates a weird situation.