Cool idea
But I warn you it will probably be insanely hard: the real engines have a specific impulse way above the one of SFS' engines: 285 seconds (which is Frontier engine, the best one ingame, only second to ion engines) is the Isp of solid rocket boosters, while efficient engines (LOX/LH2) can reach around 435 seconds. Until we can mod engines and fuel tanks, it may be extremely frustrating.
Maybe you can begin with a solar system reduced by a factor 4 or 5 (instead of 20 now).
To give you an idea, the speed required to be in LEO is:
- 1655 m/s in SFS (reduction factor of 20)
- around 3900 m/s with a reduction factor of 4
- 7726 m/s at real scale