That is a great point Ron. It is kind of a better way of saying what I said above: A contractor can play dumb a lot easier than an engineer can. It really comes down to the type of work you are doing and how you bid it.
In my case, my partner was mostly bidding public work as a contractor. He never ever advertised himself as anything but a run of the mill contractor. As I said above it both helped and hurt him, but mostly in his case it hurt him, because he could not play dumb that well. He just did too much thinking on the clock when the competition would play dumb and write change orders. Liability wise I don't think the public works stuff had any problems, there are plenty of PE's working for contractors, and PEs owning construction companies. Get the insurance, get the bond, bid the work, do the work, pass your inspections, and make sure the paperwork meets the contract requirements.
I spoke with him regarding liability during design/build work. In the cases where they did a design/build thing for a private owner, they typically would add liability insurance riders of some persuasion to cover the engineering. In some cases the liability rider required us to hire outside engineering review of the plans as well. In one particular case we could not have the owner of the construction company be the EOR, so we had to hire another consultant to be the EOR.
To the OP it comes down to what you plan on doing and how you are going to represent yourself. I am sure there is an insurance package out there that will cover you. If you are going to be an EOR and do the construction, you should check with the owner to see if they have specific insurance requirements for design/build projects.