IMO, if your wife is not into pee, its better pay a girl to play with you than you try to convince your wife. The person who is not into pee, mostly HATE pee, so maybe its better do not put you marriage in risk, pee play is stressful and discusting for those who not enjoy.
Its very rare to find a girl who truly like pee play. Even if find, she maybe can be crazy, druk addicted, a bitch, idk... The point is: If is difficult to find a girl to marry, find a girl who you can marry AND she is into watersports is even more dificult, so, accept that and graceful just pay a bitch to satisfify y