Again regarding step 4:
“Cumulonimbus cloud… … the maximum possible distance to the top of the cloud is 450 km.”
“Clouds do get higher up. Noctilucent clouds can be found higher up at 85 km. This means they could be seen from up to 1,000 km away”
“typical, run-of-the-mill, non-storm Cumulus cloud? Those can normally be found below 2,000 meters and are less than 160 km away”
https://www.quora.com/Meteorology-On-a-clear-day-how-far-are-the-farthest-clouds-you-can-see
So if the lines pointing in the direction of the sun and moon are always made to be 1,000 km, with a mark at 450 km and on 160 km on the map, this would give a good first approximation to answer if the forecasted clouds would block the sun/moon or not.
=D