Question about “group sex × travel”

I know several male members at Universe (all of them are company presidents). There’s a young woman I’ve been seeing for about a year since I made her an offer (she has since left the club), but things are starting to feel a little stale, so I’m thinking of trying a group experience. Apparently, when she went to the beach during the summer of her freshman year of college, she spent the whole night being passed around by four men, including her boyfriend, and said she experienced the ultimate bliss—so I think she has the right disposition for it. If four men participate, should her allowance be four times the usual amount? I feel like doubling it might be enough… Or would a woman generally expect more than an amount based simply on the number of men? I’m planning a two-night, three-day trip to a hot spring in Tohoku this winter, or Okinawa next summer. (She wants to visit both places.) Her current pay-per-meeting rate is 40,000 yen, so a simple calculation would be: 40,000 × 4 men × 2 nights = 320,000 yen 40,000 × 4 men × 3 days = 480,000 yen But considering the current atmosphere of our relationship—it’s casual, not focused on money, and fairly relaxed—I’m thinking around 200,000 yen might be appropriate… I’d especially appreciate candid opinions from a woman’s perspective.