Can you post a sketch of how the stringer will be cut?
Hello. I would do the following...use a double stringer. One notched as you show it nailed to another on the outside that is not notched.
Two supports like you show will work. A more elegant solution would be for the two outside stringers to be doubled, but only one is notched. The outside one would be a full stringer, the inside one would be notched and they would be nailed together. That would require no intermediate supports.
Hello Rob. I appreciate your desire to learn, but I can't get into engineering lessons online or we'll be discussing this for weeks. I will opt out for you.
Of course I do the engineering. I take what I do seriously. First you determine the allowable capacity of the beam based on the notches (there is some judgment involved, because the NDS doesn't address the stress concentrations associated with abrupt changes in geometry) and then do analyses to determine what spacing of supports results in a moment demand that is lower than the moment capacity.
I don't provide calculations and the multiple equations as the basic service. Good luck with your project