would it be hard to add transparency to clothes? perhaps make wet clothes more transparent?

We will add it to the fast option with new release.

Awesome, Transparent clothes will makes clothes even more sexier )))

It would be great to have it tied into watersports so pissing on clothes makes them transparent.
Is this do-able?

The 'wet t-shirt' effect is possible. It would require the particles to collide with the cloth, just like the body.
The cloth then should get wet (more transparent), where the particles hit (just like with the body).
We had not thought about this yet, thank for pointing it out.

I hope it's something you can add in the next version!

Good suggestion!