While I don't recommend it to anyone either, I have almost always lifted at home by myself and have no issue going for 1RM's. There is a proper way to do it. For me, I build up to the weight consistently so I have a good idea whether or not I will be successful in the lift. In the very rare instance I am not, I lay the weight down and roll it across my stomach to my hips, sit up and then move it off me to the bench. It's actually become quite easy. I used to practice this with lighter weight so that I would know what to do if it ever came to that.
Don't try this at home kids. ;]