He has been there since November of 2008, which is long enough, for any houseguest, regardless of what problems they may have.
You and your husband have been extremely generous, really to a fault here. You have given him the impression that your house is his house, and four dogs are better than two, and six dogs are better even still.
Extra cleaning, cooking, expenses. I presume that he was on some sort of benefits to cover the time he wasn't working due to the workplace injury then the motorcycle accident. He is able bodied now, and now is the time to let him, and his univited girlfriend, that they have until the 15th of the month to move, and move WITH their four dogs. I have a vision of them leaving, and leaving you with the dogs, particularly if they are going to be renting.
You really need to think of your own family here. My husband would not have remained silent for over a year while a 'houseguest' overstayed their welcome.
Like most people, you would have presumed that his stay would be temporary, then extend that when he had the motorcycle accident, fair enough. But, this is turning into a nightmare, and it has to stop. It is not fair to your husband, and your daughter (or the dogs).
Speak to him on a certain day at a certain time. Say, tomorrow night at 7 p.m. You and your husband tell him that although you realize he's had trouble with the accidents etc. you would appreciate him moving out with his girlfriend, and the dogs, by the 15th.. It's that simple. If he gets angry, or feels hurt, or can't believe you said that, well, too bad. He doesn't have the sense God gave him to know that he doesn't move in with you, then move in his girlfriend, then move in his dogs, with no plan to move out.
Don't negotiate, discussion is over. He needs to be on his own two feet. If he is strapped for cash for first and last, he can approach welfare or organizations like the Salvation Army. Regardless of what needs he has, as an adult, he needs to solve his own problems, and solve them without any help from you.
If he stays, you have nobody to blame but yourself. He cannot take further advantage of you, if you don't allow it to happen.
Take your life back!