When I joined the OGF I quickly realized that mapping on blank paper is very hard. So, I tried to print my country, draw something on the paper then trace this in JOSM. But all online services work only with OSM.
Then I found project BigMap2: https://github.com/Zverik/bigmap2
I installed it on my linux server, added OGF tiles links and now I can generate image of any place in OpenGeoFiction with any required details.