I think taking all the current mount locations and changing them from their current plaque or stand type and setting them to hard points that you could then pick and choose what mount you want to place there would be ideal. So if you don't want any small plaques in your lodge you could choose medium or large. Same with stands, because it'd be nice to place more large multi-mounts around.
Also don't limit the size of the animal to the size of the plaque or mount. Sticking a jackal head on a medium mount looks wrong and should be able to be placed on a smaller mount.
Adding to the customization choices, like others have said, have different terrain types for stands you can cycle through for your preference. Winter MedVed, Africa, Rock ledges (bigger animals or groups of small game).
I think the biggest and most complicated option would be to have a base structure for the building, but then have multiple skin options for what it could look like. Choices between things like log cabin, Spanish stucco mission, Mediterranean, European, etc. They could add new skins for it periodically over time. The base structure could have a massive great room that was open for two stories with a giant mountain stand in the center with walkways going around it on both levels to view your trophies. Then have many other smaller rooms of varying sizes making up the remainder of the structure with the hard points I mentioned above to place any other trophies on. This way players could have a lodge that can be built multiple times but each could look vastly different from each other.