Just do what you feel right, Karlaa. As a few of us have said here, accepting cc is a good move.
I don't see it as profiteering. Many businesses charge additional for cc, I only have problems with those that have majority of their transactions in cc and still charge for it, like you say, that situation doesn't apply here. As to the amount, you charge what you think is justifiable. As most of us know, the cc companies aren't exactly kind to small business, especially those in this industry!
Reviewankly and personally speaking, a flat fee, like you charge, is a lot better than a perceneforum.xxxe. I'd prefer $0, but that's another story.
For long (i.e., multi-hours/days) bookings, carrying large amount of cash just isn't feasible or smpe. I hate carrying cash. Under normal circumstances, you'd be lucky to find more than $20 in my wallet... (Currently, I've $1.65...)
Part of the benefit for paying by cc is to earn airpoints, so I can fly up to the Gold Coast, for example...