Yeah,but it has some drawbacks:
1. You will have to install all of the "perfectly-running" mods again,in case when only ONE freshly installed mod messed with your img file.
2. You should be possessing BOTH of your CDs.
3. It'll take a significant amount of time.
Your idea is very nice P'Bull,I appreciate it.But ironically,it has got some drawbacks.
CONCLUSION: Do not mod your files before taking backup EVER!