Let's put them all here.
Non commercial teams. Amateur cycling clubs are invited to put forth a team. Team expenses and rider salaries are covered by the tour. Every team gets the same budget. Every rider gets the same salary. Teams and riders may not accept $$ sponsorships or other salaries while on a tour team. In kind sponsorships of equipment and services come out of the team budget to keep the playing field level.
Medical services are provided by tour doctors.
Sponsors may sponsor the whole tour. Provide money for ads, bikes/equipment for riders.
Make being invited to participate in the tour a huge honor. If a rider/team cheats, it's a huge DIShonor. Teams can be punished by ejecting them from the tour, and not asking them to participate for a number of years.
Any windfalls from winning come from personal sponsorships after a rider is finished their riding career. If they get caught cheating, this will likely evaporate completely.