I have to admit I have no idea what agglutinative or inflecting means. :D

I do think that rather than having a different word for each form of sex there's a root that stands for sex -- perhaps two or three, as you said "sex for fun" versus "sex for children" and such -- and prefixes and suffixes to indicate what positions and genders and such were involved.

So, say boai is the root for sex for fun -- boai itself is based on bo, which is infinitive of the pronoun ("ba sich" is ba -- declined pronoun, I have, and sich -- faith, in the religious sense). Boai is bo -- which means I Give, and ai, which means joy.

So you would have boai as the base, and then say perhaps tanboai would mean male gay sex, and tanboai'bo would mean male gay sex where the speaker topped.

I do love language geekery :D