OK now I feel stupid. Just tested with a clean 1.8 install. The option to use the magboom as a resource scanner only appears if you disable stock scanning in the SCANsat settings:
Well you've got two copies of the FireSpitter DLL and some of your mods are slightly out of date but I don't see any that were compiled for 1.2 .
Other than that the crash occurs immediately after the log entry:
Now it could be a problem with that part or (more likely) with the next step in the loading process which is to begin compiling IVAs. Judging by your GameData screenshot, the first mod with IVAs would be Mk2Expansion. Perhaps start by checking you've got the latest version of that?
On a more general note I'd recommend making a copy of KSP outside of the Steam folder for modding. Steam's auto-updates and some of Window's protectiveness about the "Program Files" directories can sometimes cause issues.
Just noticed the version number in your picture is showing 1.3.0.0 - the current version is 1.3.0.1804. This suggests the buildID64.txt file is missing from your KSP folder. I just did a test and if this file is missing then the watermark is always shown irrespective of the setting for "Display version watermark..."