I am a near 40's male, married to my wife of 13 years. We have always strayed on the dark side in our relationship, but my wife hung up her Mistress moniker and we mutually decided that Hot-Wife and sissy husband was our preferred lifestyle. We both identify as Pansexual too so size in all respects does not rally matter. 

We have recently signed a contract granting each other an open relationship, her side of it is straightforward in that she is able to have an affair with anyone she wants, and how many partners she has at any one time is irrelevant. However I am limited to same sex or pre-op TG partners (or a MF couple where the M is a Bi Dom) as my wife thinks I need to learn and be used to sucking cock and taking cock before she lets me join in any one of her dates with any lovers, I have yet to take part in a threesome with my wife as she does not think I am ready and thinks I need trained, I have been trained by strap-on only, although I have been in the presence of her being fucked really well on at least one occasion.

My wife's other request is that the new partner (or partners) have to be cigar smokers or smokers that would like to smoke cigars, my wife smokes them and loves the power it gives her, she uses it as a tool to get what she wants from me and uses my mouth as an ashtray, she berates me too and wishes for my new partner(s) to do the same, the only caveat is that no marking of my body is to take place, although slaps and the odd crop mark is fine.

MM/MF couples are welcome too as long as they fill the brief and my wife agrees to it, you would also be able to accommodate and you must be a top or tops.