If you need a contract, this isn't the lifestyle for you.
If you must write down boundaries and expectations, then you don't have the communication in your marriage to endure a cuckold relationship.
If you need your wife to sign a list of your fantasies and insecurities, and expect it to be regarded as law and protection from heartbreak, you are delusional.
At the end of the day, it's about trust, unconditional love, and communication. Either you have it or you don't. That piece of paper you printed off a cuckolding website isn't what is going to make the relationship possible and prevent your wife from either leaving you or ignoring you altogether.
Want to find a playmate/Bull for your wife? Guess what the biggest red flag is for ethical Bulls? Those stupid rules and restrictions. I am not talking about the common sense ones that pertain to safety and sexual health. Asking everyone to get tested before playing is fine. Asking for sex safe practices is fine as well. Requesting that if unprotected sex is desired that sexual exclusivity or a commitment to one bareback partner is not unreasonable.
What is unreasonable cucks, is when you tell your wife how she is allowed to play. Cucks ask their wife to agree to "Not Kiss the Bull", "No Anal with the Bull", "No domination by the Bull", or one of my personal favorites "If you develop feelings for the Bull you agree to terminate the relationship immediately". Other absurd requests are "You will share every detail", "You can only date him every so often", "You will fuck only superior black cocks", and "No doing anything with him that you don't do with me!"
You want some advice? Work on your communication with your wife. Let her lead the relationship and affirm that you will trust her judgement. Be an amazing husband in all other regards and make life as stress free as possible. Do NOT make this about you. You will fail miserably, and it will end in tears. As a cuckold you won't get to make the rules. You submit and obey them, or this isn't for you.
But cheer up because the Bull doesn't make the rules either. They are made by the wife. While a bull can respectfully decline a request, they don't get to force the wife to do anything they want. If your wife says "The Bull has demanded that I only have sex with you on your birthday and you'll be wearing two condoms so you aren't really touching me." That isn't coming from the Bull. Your WIFE had to consent and agree with making that imposition upon your relationship.
If she wants to do something, she is going to do it. You can't "halfway" give your wife sexual liberation and freedom. She is going to do things with another man that she doesn't do with you. You are in a completely different relationship type. If you are a cuck, chances are you have never been rough with her or dominated her in bed. Maybe, she's been secretly desperately wanting a stud to rearrange her insides and choke her while she climaxes and soaks the bed with her orgasm? I understand it's hard to hear that. but it's only going to happen if SHE wants that in her sexual relationship. Once you decide to become a cuckold, you must accept that her sexual relationship with another man is none of your concern anymore. Sure, if he is abusing her against her will, gaslighting her, or unduly interfering with your marriage -- then definitely take your testicles out of your wife's underwear drawer and strap them on for a confrontation. But otherwise, you need to let go and trust her judgement. Best thing you can do is be unconditionally supportive.