OSHA 1926.51: does a 'mobile crew' exemption apply if the nearest bathroom is 10 minutes away?
OSHA 1926.51 does not exempt your crew from providing a toilet on site if the nearest bathroom is 10 minutes away. The mobile crew exemption applies only when transportation is readily available to toilet facilities, meaning immediate and unimpeded access without significant delay. A 10-minute drive each way disrupts work and does not meet the 'readily available' standard.
OSHA's mobile crew exemption requires that the crew has transportation, like your van, and that the toilet facility is nearby enough for quick use without productivity loss. Ten minutes away is too far; OSHA expects facilities to be on site or adjacent. For 12 workers, the standard mandates one standard portable toilet minimum.
Your setup with a van does not change this. The exemption is for crews moving between sites with rest stops or facilities en route, not for fixed sites with distant bathrooms. If your cell tower work keeps the crew in one location for hours, you need a unit on site.
Placement and service for a standard unit is straightforward. It needs level ground and truck access for weekly service visits. Rent one, avoid fines and crew complaints. Anyone dealt with similar remote sites?