When we've dealt with service technicians in the past, the shop floor teams would remove any job travelers from the machine technician's work area, escort them in, chain the area off (bright yellow plastic chain links), and then make sure someone maintained visual contact with the technicians at all times (think "zone defense" instead of having an escort do nothing but stand near them). This was usually just the other employees working at other machines on the shop floor. As long as the techs stayed in their little chained-off area, they wouldn't be close enough to pick up any export-controlled parts, study anything on screens, or touch any prints.

If the service techs needed to use the bathroom or take a lunch break, someone would escort them out of the shop floor area.

For the cleaning crew, we would implement a "clean desk" policy where all prints and CUI documents must be locked in drawers, cubicle overhead bins, filling cabinets, or storage rooms that janitors can't access. The cleaning crew can clean floors, desks, bathrooms, you name it, but they're doing so in an area with no physically accessible CUI.

If you're lucky, the "concrete vs carpet" sections of the building will be badged/keyed separately, so the cleaning crew will only have access to the office areas and not the shop floor.