I realise the question is about you not having enough people to write references for you, but what we did was to write an exaple of the reference needed ourselves and ask them to print it on their headed paper. That way we got what we needed them to say.
I had a problem like this as most of the garages i had worked at over the years had dissapeared. My agent said if i could track any of my workmates down they will accept stat decs/affa davids signed by them in front of a solicitor. This was a difficult job going back 20 odd years but i managed it through word of mouth (mechanics are like old women when it comes to gossip) and here i am in oz.
Its all good
I had to do all that for my OH. Before we met he kept no records at all. We had the same problems. I tried the tax office and they took months and were about as much use as a chocolate fireguard. We did a CV for the companies that Jason had worked for as a subbie, some of it through guesswork and some of it from help from a friend of a roofing company who Jason had worked for on and off for 10 years. We had too do a stat dec and get it signed in front of a solictor saying that all the info that we had provided was the truth. Jason also had to think about people he had worked with for the same company and they then did references for him. There was some compnaies that like youself that Jason did not patricularly get on with in the end so we just did not get references from them. We supplied 1 x supplier reference, 3 customer referecnes and five work references - this may have been a bit over the top but the way that we looked at it was the more the better.
Hope this helps somewhat.
Jason & Niki