not to demotivate you, but some of the most amazing stuff i stumbled upon by chance on pixiv wasn't tagged in any specific way, other than the obligatory R-18 or R-18G tag. Worse still, some stuff with very clear guro vibes will not be tagged as such, so you will only find it by chance, if at all. But if you ever do find something good, make sure to like&fav it and follow the artist...

輪切り　- round slices (or discs) imagine cutting Guroccubus in slices like a vegetable xD

one example for random find: ttp://www.pixiv.net/member_illust.php?mode=medium&illust_id=46532957

it's not tagged in any straightforward way, but 遠距離ックス means long distance sex. see for yourself how it's done.