This does smell a bit like a "throw together a lot of high-tech buzzwords" design exercise more than a real product. First, series hybrids are generally a bad

This does smell a bit like a "throw together a lot of high-tech buzzwords" design exercise more than a real product. First, series hybrids are generally a bad idea for road-going vehicles, where a mechanical link is a) pretty straightforward and b) a lot more efficient at cruise, which is where fuel economy really matters for most applications. Secondly, gas turbines are primarily an advantage where power-to-weight ratio is important (much more of a concern in, say, a helicopter than a heavy truck). They are generally less efficient than diesels, especially at the size needed to power a truck, and even more so when running at less than full power. (Incidentally, diesels are pretty trivial to convert to run on CNG). This approach (minus the energy storage) has been tried for locomotives and found to be lacking: https://en.wikipedia.org/wiki/Gas_turbine_locomotive https://en.wikipedia.org/wiki/Gas_turbine_locomotive.