The campaigns of 1805, 1806 and 1813 were fought around there, so after some research I'm convinced you'll find something.
It's undeniable that the Ridge on which the allied army was deployed was messed up due to the construction of the Butte de Lion. However, I must remind all of you, the Butte is not a monument solely dedicated to the Prince (Even though people, especially Brits, like to say it was), it's simply built on the spot where he was wounded. The monument is dedicated to the participation of the NL troops, from the highest general to the lowest private, Dutch, Belgian or Nassau. Besides, it's gives a great view over the battlefield.
The construction of the tram line (Not sure when that happened) also did a major contribution to the destruction of the ridge, which is often forgotten. The rest of the battlefield, by the way, is still in good shape. Minus Hougoumont of course, which is falling into ruins but which will be repaired. So they say.
Talking about monuments, the British truly have no right of talking. They smacked the battlefields and even the walls of Hougoumont full with monuments dedicated to British soldiers, even though the British were a minority of the defenders farmhouse. It was largely defended by Germans (Including the 1st battalion of the 2nd Nassau Regiment), but that's of course carefully ignored.
a monument Wellington himself said ruined the battlefield
Is it actually proven he said that? As far as I know it only shows up in a book by Victor Hugo.