Small Excavator Excavation Enhancement

Landscaping is on the large 4x4 grid, while walls (and everything else in the game) are on the smaller 16x16 grid. Since you can't excavate in the same tile as a wall, frequently, temporary walls and a lot of intermediate steps are required to build clean steps for infrastructure. Perhapse the small excavator could have a mid to late game enhancement where it can excavate on a 8x8 grid (2x2 of the building grid). This would allow cleaner placement of walls and permit digging around them to optimise the space below them.