re: Cutting Corners?
The Viking and Voyager probes were originally intended to be launched by Saturn 5 rockets but they were made smaller, launched by Titan IIIs and were ultimately very successful!
I've always been very seduced by the General Dynamics ELA project.
Perhaps not feasable, but it showed existing slightly upgraded rockets could do it.
Those rockets could always be used for other missions (not moon related).
When it's about humans to Mars, the scale is quite different!