I'm currently involved in one of these in 5E, it's a lot of fun. Our party members include:
>>Secretly futa tiefling paladin aristocrat with the strange ability to end up padded yet retain dignity, frequently finds herself seducing
>>Crossdressing tiefling cleric boy with a magical girl wand that lets him transform into the rough equivalent of diapered madoka,
>>Human male sorcerer who foolishly equipped an unidentified pair of underwear from a dungeon and has since been permanently(?) genderbent, losing int and gaining charisma over time as a result of the curse. Also frequently rolls the chaos table with amusing results.
>>Incontinent human female arcane trickster rogue, playful evil, causes lots of amusing trouble by screwing with people but does it in good faith. Abuses the prestidigitation spell to clean up her diapers. Avoids sexual situations but frequently finds herself the subject of fetish hijinks.
>>Grungy human male fighter specializing in fencing. He's basically a rogue that traded backstab for battlemaster traits. Has a developing thief partnership with the trickster rogue. This is my character. My intention going into the campaign was to play him as the straight man and I've largely succeeded, but he's been stuck with a strange magical ailment that genderswapped him for a little while and now allows him to change gender at will - which is incredibly useful for pulling disguises. Being a nonmagical character makes me feel a little underpowered so I'm sort of playing it off like he's interested in learning magic from his trickster buddy, but we'll see how that pans out.
All in all it's a really neat campaign. It's fun to really bend the D&D mechanics towards fetishy stuff and see how some of the more obscure text applies. For example, prestidigitation and several similar spells all mention that they can clean small messes in a certain radius, which we've interpreted to mean diapers - so everyone with magic can just give each other magical diaper changes at will. The DM is also a complete clown so it's very unserious most of the time, as befitting a fetish campaign IMO. And we've only had one real sex scene! Good times.
>>tfw of all the campaigns you've been playing the /d/&d one is the only one that lasted more than 3 sessions
I guess it can't be helped.