I am just using KSPRC with SVE clouds, second picture is orbit around jool.
As for engine that (iirc) the LAE from SSTU mod pack (wanted to test that too), nice little mono engine. Thrust wise I can not remember, but iirc I had +1TWR (a little overkill) and around 1.2kdV with 3 stock monotanks attached ontop of your stuff.
As for size this is maybe the smallest I go, I am kinda trying to get out of the habit of cramming as much science onto one thing instead of it all making sense and planning out extra progressive missions.