Fixed prices, by the day
One national rate table, the same one this site publishes. No regional pricing, no multi-day discount, and one to seven travellers pay the same price.

Your plan already knows which days are hard to do by train. On those days you can add a licensed guide, a car with a driver, or both, at a fixed price shown before you book.
One national rate table, the same one this site publishes. No regional pricing, no multi-day discount, and one to seven travellers pay the same price.
A licensed travel agency confirms who is free on your dates. Nothing is charged until it does; then 30% in the app locks in the guide and the car.
The agency, the guide and their licence numbers, what the day includes, the insurance, and a six-character pairing code to check before anything else happens. It works offline.