The module was expected to contain an assembly manifest

I found that, I am using a different InstallUtil from my target .NET Framework. I am building a .NET Framework 4.5, meanwhile the error occured if I am using the .NET Framework 2.0 release. Having use the right InstallUtil for my target .NET Framework, solved this problem!

BadImageFormatException, in my experience, is almost always to do with x86 versus x64 compiled assemblies. It sounds like your C++ assembly is compiled for x86 and you are running on an x64 process. Is that correct?

Instead of using AnyCPU/Mixed as the platform. Try to manually set it to x86 and see if it will run after that.