I did just that and suggest some research of companies and their exclusions, etc.
My expeience with one very big case was quite good with a very generous company. Can they generally explain their past practices on actual claims? They probably want some guarantee that you use a certain form of contract on every job.
If you have a claim will they drop you? If so, you will have tough time getting any other company to cover you, becaues you will have to state the dropped situation in the application.
I'd add one other thing. If married and in a state with marital property laws, see sbout diverting yourself and wife from that requirement and also then gift all your assets to wife, except for retirement funds (assuming that can't be attached).
Then, each job has to have that client know of your marriage arrangement and a contract that states such wife assets are immune from claims. I add a "terms and conditions" on the back of every invoice also to help cover this, just in case.
Tbis "may" help in case of no insurance, but who can predict what lawyers can accomplish.