Most of the shooting schedules include VANITY VANS which are often large , spacious and luxurious and have a Toilet, Bathroom and a tank with 275–600 liters of water depending on the model
Even so some locations don't allow Vanity Vans due to their height or remoteness
Like Mungaru Male (2006) where Actor and Actress - Miss Gandhi (True name 😁), spent 9 hours to film a perfect scene under perfect light at the top of Jog Falls in Shivamogha
In these cases there is what is called a Change Room nearby
In this case around 10–15 kms away (50–60 mts by car) where the cast can go, rest, relax, do their business and have lunch in an emergency
I must however tell you I pity women in this particular situation even during long drives
Men - find it so easy to get out of the car, walk to the corner of the highway, gently stare at the sky and finish the business in 2–3 minutes
Nobody cares
But women- they have to suffer in silence until they reach some motel or petrol station and request the guy to allow them to access the rest room
Such scenarios are very rare though
Shooting in remote locations these days is very tough due to SKY high insurance rates
If someone like Ranveer Singh has an accident from Jog Falls - his life is insured for ₹500–800 Crore and the premiums are as high as ₹40 Crore
Much easier to ask the unit to make a normal location look like a remote location or to use a GREEN SCREEN