My mom uses a walker. Is a standard porta potty okay for her during our remodel?

No, a standard portable toilet is not suitable for your mom who uses a walker. Upgrade to an ADA-compliant portable toilet for safety and accessibility. The ADA Standards for Accessible Design require features like a wider door (at least 32 inches clear), grab bars, a higher toilet seat (17 to 19 inches), and a larger interior with a 60-inch turning space for wheelchairs or walkers. These make entry, maneuvering, and use much easier for someone with mobility issues.

For your household of three adults, one ADA-compliant unit would suffice, as it meets both accessibility needs and general use. OSHA 1926.51 sets minimums for construction crews, but for family use, the portable sanitation industry guideline suggests one unit per 50 to 75 people for short events, which your situation exceeds comfortably. Since you're on a flat driveway with good truck access, placement is fine. Weekly service is standard, but if usage increases, you might need more frequent pumping. A restroom trailer is an alternative with home-like features but requires power and leveling, adding complexity and cost. Stick with an ADA unit for simplicity and compliance.