It would be great if you could walk over them. I think you need to set the collision_mask on the item's prototype. Another mod that added flat buildings that you could walk over (Advanced Fluid Handling) used this collision mask:
afh_walkable_mask = {layers={floor=true, item=true, object=true, rail=true, water_tile=true, is_lower_object=true}}

I'll test and release it later today hopefully

Done and released. Seems to work just fine with the mask you found, good job

Thank you! Happy I helped make it easier.