Jeff ManI do not know of standard pre-nup contract for cuckolding, but my opinion is that you should find a lawyer to draw one up that has the following components:
1) A clause that states that the impotence of the husband and his inability to perform sexually shall NOT be grounds for divorce. [Even though you may be having good sex with your wife now and in the future, this clause both protects you from her running off in the future with one of her lovers and sets up the strong justification for the later clauses. In the event you she cuckolds you completely, the lack of marital sex will not be grounds to dissolve the marriage.]
2) That the marriage remains binding and in power even if the marriage is never consummated or consummated on a periodic basis. [Similar to the first clause, in some marriages, the husband never has sex with the wife. In some states, this is grounds for annulment and this clause should prevent the ability to dissolve the marriage on those grounds.]
3) The husband understands, accepts and agrees that his wife has a normal functional sex drive and that despite his inability to perform sexually, in order to ensure marital harmony he will take no action to prevent the wife from having be fully and completely fulfilled sexually. [This clause opens the door for the wife to seek gratification outside of the husband.]
4) The husband understands, accepts and agrees that artificial devices, including but not limited to marital aids, dildos, vibrators and penis extensions do not represent acceptable alternatives to ensuring that the wife is fully and completely fulfilled sexually. [This prevents the husband from claiming in court that he can satisfy the wife with sex toys.]
5) The husband understands, accepts and agrees that the only means by which the wife can be fully and completely fulfilled is through natural intercourse.
6) Given the husband is not able to provide acceptable natural intercourse, he understands, accepts and agrees that the wife be provided with surrogate sexual partners.
7) Sexual intercourse with surrogate sexual partners is to be construed as to be completely within the confines of the marriage and does not represent the breaking of marital vows.
8) The husband understands, accepts and agrees that due to his disability and the fact that he accepts responsibility for maintaining the sexual fulfillment of his wife, it may be necessary for him to procure, solicit or otherwise arrange for the services of surrogate sexual partners for the wife.
9) The number of surrogate sexual partners shall not be limited in any way.
10) The frequency of surrogate sexual relations shall not be limited in any way.
11) The characteristics of the surrogate sexual partner shall not be limited in any way, to include but not limited to physical proportions, race or demeanor.
12) The husband understands, accepts and agrees that pregnancy is a natural and acceptable outcome of the relations that the wife has with surrogate sexual partners. Further, he agrees to accept any pregnancy as if it were conceived through his own actions.
13) The husband will support the wife during each and every pregnancy and assist her in any and every way to carry those pregnancies to term.
(choose one of the following
14a) The husband will allow his name to be placed on the certificates of birth regardless of whether or not identifiable characteristics of the youngren may preclude the husband from being the natural man of the young.
14b) The husband will allow the name of the natural man to be placed on the certificate of birth. In the event that the natural man of the young is not know at the time of birth, the certificate of birth will clearly state that the man is UNKNOWN even though the marriage remains in power.
15) The husband understands, accepts and agrees to support any and all youngren that are born within the confines of the marriage as if they were his own. In the event the marriage is dissolved for reamisters other than those set forth in this contract, the husband aggress to pay young support for any and all youngren born within the marriage as if they were his own.
There are probably a lot more things to cover, but I think this is a good start.