You’re over thinking this. To make this simple. There are ppl that hire for an hour or 2 or even an overnight. That market is established and the power dynamic is usually with the provider. He commands the price and terms. In an arrangement situation like yours, where the client has an abundance of resources, the power dynamic can get flipped. Especially in this situation, based on what you described the power dynamic is very much with you. You’ve done this before, you’re experienced in these arrangements. If the intimacy is defined and lines have been drawn between what you plan to or don’t plan to engage in, then you can tell him in addition to covering costs I’d like to pay you $x per day. You’ve had enough of these to know what’s fair. If he exceeds those expectations you give him a tip.