Anyway to workaround .NET 4.0 framework outside/inside Unity?

Hello again.

Now, I am (still) trying to handle the Canon SDK (dll) [by / inside / outside] Unity.

For this moment, I had some ideas (speculations) and want to hear your opinions.

>PS: As part of the agreement from Canon. I am not allow to reverse compile the SDK and then compile it to 2.0 to solve the problem.

1. Create a new .dll plugin compile by .NET 2.0/3.5 . And include Canon SDK (dll) in new dll so I can call Canon SDK by new .dll . (Currently working on this)

2. Write an C# script in Unity make Unity start an new application in background, which so we can use this to handle Canon SDK. (Currently 100% no idea how to do this)

Please tell me that do you think this way could work ?

PS :

1. You can check my last question about "Can I use .NET 4.0" . I post the error message there.
   

2. As English is not my native language so if there are any grammar mistake or not so sure what I am saying. plz feel free to leave a message in comment section.