I looked into this for connection new service laterals to the vacuum line and I never did find a wye saddle that works. You can always cut the pipe and slip in a wye with gasketed coupling.
The most important thing about your proposal is the gpm that will be pumped. Each valve should receive 15 gallons per minute on average, each valve can handle more for short periods. Just add additional vavle pits to the location where you will receive flows. The absolute most important thing...