You may wish to consider making a homemade PAPI.
PAPI differs from a VASI (often the descriptions are interchanged) in that PAPI is a projector system and thus can be very accurate. PAPI is like an old style 35mm slide projector. It requires a white/red ‘slide’ defining the boundary of high/low, a suitable lens to focus the beam, a light source, and a containing unit.
IIRC early test versions (RAE Bedford) were made from clear plastic sheet / coloured glass or stick-on plastic. The lens was the most difficult item to find – unless you have a spare HUD. The casing was a large diameter plastic drain pipe / gas pipe / water pipe, depending on which utility was working in the local area. A bubble spirit level was preset to the required angle and stuck on the side; I assume that your system will be level. (With due acknowledgment of engineer extraordinaire Mr Sam Kidd, RAE circa 1970s).
As an alternative there are some cheap and relatively powerful ‘laser’ type lights (presentation pointers) which are effective over reasonable ranges and might be seen in daylight – use a target board on the excavator and a spirit level on the light.
In Canada, try ‘Canadian Tire’ for a $6 light / pointer.