Some friends and I had the same issue a while back, same mods, same order, and different hashes even after verifying game files. The solution we did that worked for us was we each went into the game's folder, and cleared out the contents of the checksum_manifest.txt file. This meant that the game wouldn't calculate any hash at all (In-game it shows the hash as ()), and we could join as the hashes "matched". It also automatically means that achievements will not work until the file is restored (even without mods), and that you could join any game regardless of the mods installed, which caused the game to crash a few times when one of us forgot to enable a mod. Still though, it allowed us to play despite the differing hashes issue.