Past Employer is Out-of-Business - How Do I Prove I Worked There?

I am currently in Canada with an Open Work Permit and I am currently working in a job at skill level "0". I am applying for permanent residency through the "Arranged Employment" track of the Federal Skilled Workers Program. Before coming to Canada, I worked for several years in another job at skill level "0" with a tourism company. That company unfortunately closed down in 2008. I need the points from my work there in order to have enough points to qualify for permanent residency. What should I do?

For this situation, the Immigration Canada website says I should do the following:
"If you cannot provide a reference from an employer, provide a written explanation and any documentation that would support your claim to such employment and provide the information as set forth above."

Aside from one of my old employee badges (which states my name with a photo, but doesn't mention my specific position), I do not really have much other documentation (no pay stubs or old work contracts) to prove that I worked there. However, I am still in touch with my former boss from that job, and he now works in another company. He says he would be happy to write me a notarized letter of reference on official paper from his current job, explaining the work I did with the now-defunct old company before it closed.

Would this be sufficient? Is it likely that CIC is going accept this as proof? What else can I do to demonstrate that I really worked there?