Doesn’t work that way. Septoria is a disease that a plant can grow out of to some extent. Reduce the fruit load and the plant can devote more energy to rapid growth. Drought resistance in tomato is more a function of having a large root system. This gets down to having a vigorous plant. Graft onto a very vigorous rootstock and septoria damage will be significantly lower. Again, this is not due to an inherent resistance, it is a more vigorous plant that can produce more alkyl sugars which promote leaf health. It is correct to say that breeding for a more vigorous plant is making a super plant, but the effect on septoria is indirect.
If you dig around online, you can find a study from Brazil showing several lines of wild species with significant resistance. S. Chilense and S. Peruvianum in particular have much better overall disease resistance than domestic tomato. Unfortunately, crosses to these two species require embryo rescue which I am not set up to perform.
I’d like to say that there is a ready genetic solution to septoria, but the reality is that it is going to take a lot of work and probably some genes from wild potato species to do something significant. Crosses to diploid potato are possible via somatic fusion. Worth noting that pepper is generally immune to septoria. Unfortunately, the genetic barriers with pepper are far higher than with other tomato species.
Including Solanum lycopersicum, there are currently 13 species recognized in Solanum section Lycopersicon. Three of these species—S. cheesmaniae, S. galapagense, and S. pimpinellifolium—are fully cross compatible with domestic tomato. Four more species—S. chmielewskii, S. habrochaites, S. neorickii, and S. pennelli—can be readily crossed with domestic tomato, with some limitations. Five species—S. arcanum, S. chilense, S. corneliomulleri, S. huaylasense, and S. peruvianum—can be crossed with domestic tomato with difficulty and usually require embryo rescue to produce viable plants. The Lycopersicon section has not been fully sampled within wild species in the South American range, so new species may be added in the future.
Solanum section Lycopersicoides and section Juglandifolium are represented by two species each that are considered bridge species genetically intermediate between tomato and non-tuber bearing potato species. S. lycopersicoides can be crossed with domestic tomato and introgression lines have been developed. This species was significant in moving the domestic tomato from separate genus status into the Solanum group because it directly links the tomato into the potato family.