People might chose to acquire HSV 2 orally because it recurs very infrequently and sheds very infrequently and once you acquire it orally, you would not get it genitally. Of course, now we are talking about people who don’t already have HSV 2.
There are no known potential liver problems with these medicines. If you are reading that somewhere, I don’t believe it is reliable information.
But it is fine to take it for five days ahead of sexual contact instead of every day.