Bayo (NSFW)
I think you shall have more to contend with than sweat. Coitus tends to involve a number of other fluids. Sweat, semen, and well...if you do intend to place have a phallus very deep within one or the other of you, there is that to consider as well. After all, there is no orifice on a body that is clean as a mountain spring.
And you will most certainly want any of those activities to be moist.
But it is all as natural as walking barefoot, or sleeping or any other animal thing, so there's no need to be squeamish.