I would like to suggest getting rid of the requirement for flat paths to place bins on. The only benefit this restriction offers that I can think of is avoiding having one side of the bin floating and the other side clipping into the ground. However, this comes at the cost of having large segments of of even slightly sloped/uneven paths be absolutely strewn with litter, just because the path isn't perfectly flat and so the game won't let me place any bins down.
I personally think the cost greatly outweighs the benefit here; bins have such a small footprint that only the most OCD player would be bothered by them not being aligned with the surface of the path. The game already allows much more dramatic visual "glitches" without much complaint from anybody because avoiding them would be more computationally pricey than it's worth (guests within a group playing the same animation in perfect unison or gliding across the path because the whole group is rotating around one pivot point, animals walking straight through enrichment items, etc).
I personally think the cost greatly outweighs the benefit here; bins have such a small footprint that only the most OCD player would be bothered by them not being aligned with the surface of the path. The game already allows much more dramatic visual "glitches" without much complaint from anybody because avoiding them would be more computationally pricey than it's worth (guests within a group playing the same animation in perfect unison or gliding across the path because the whole group is rotating around one pivot point, animals walking straight through enrichment items, etc).