I personally could not write this in any progress note without palpating. I do not believe I've ever had a pt with Hepatomegally which I could visually see. So if you wish to notate this, palpate and write "no gross organomegally palpated: While hepatomegally can be present and not palpable, by inserting the clarifier "palpated" you somewhat absolve yourself if there is organomegally there that you need to percuss to find.
This advice stands only for PE/CS cases which you have no reason to suspect hepatobiliary pathology and they do not give you sufficient time to perform a full exam.