Hey. When I tried it some time ago I could confirm that it also felt very buggy. Sadly I don't think I can fix this because it might require rebuilding the entire thing.
The other issue that you mention, with boom and ballast etc is sadly not something I can fix at all. It's because hooks/lockgroups are extremely buggy in this game. Hooks have a tendency to get destroyed if you have too many objects hooked together. Then there is also the issue that I've explained here: https://forum.rigsofrods.org/threads/how-to-stiffen-hook-hookgroup-ties.799/
These two issues makes the modular concept of Badboy's LTM11200 unable to work properly. Right now I would honestly recommend my AC1000 if you want a strong mobile crane, since it's less reliant on hooks.