Whether you are on the shoulder or not, or others perceive it to be a shoulder or not is irrelevant. All you can do is be hyper vigilant and try to have a bail out plan when riding in traffic. 'Safe' cycling in traffic is a fading expectation. We live in a world of ever increasing chaos and anarchy. Increasing selfishness and lack of concern for others. What this means to cyclists are the following:
1. Even if a motorist absolutely knows it's a shoulder it won't stop them from driving long distances on it for any number of reasons that would be considered illegal if actually stopped by a patrolman.
2. Just as often they will drive long distances down a center turn lane.
3. They will not stop and often not even slow down for stop signs even in residential areas.
4. They are more addicted to their phone than any opioid ever invented.
a. They will obliviously drift across lanes until they hit something or snap out of it over correcting in the opposite direction.
b. They will run head on into stopped traffic or a cyclist proceeding too slowly.
5. More and more even stop LIGHTS are being treated as a suggestion.
6. It's a waste of tax payer money that speed limit signs are even manufactured any more. 99% of people speed. 90% of people don't get pulled over. Of that ones that do 9% pay their way out of it through sham traffic law businesses. Only 1% really get punished either due to poverty and/or race. Even in accidents involving impairment and death you already know how things are going to turn out based on the lawyer you see they retained in newspaper.
7. Slowing a motorist down for even a moment can result in a vigilante death sentence. They will gun for your back wheel, fail to fully change lanes because they want to intimidate you by passing too close. I'm not talking about squeezing you because the left lane is taken. I'm talking not another car in sight, but it's just too damn inconvenient to move the wheel 1 or 2 degrees more. It's like they are thinking god dammit you piece of ****, you have no right to go slow enough I have to make a lane change. Likely because you caused then to stop texting or watching video, or playing video games. Yes I've seen people doing all those things while driving. I've had one incident where driver took it far enough, that I'm certain he would have hit me if I hadn't bailed into drainage ditch. Pickup truck pulled alongside and took a hard swerve at me to the edge of pavement. It was a twisty semi-residential uphill along a park. They got pissed it took so long to find a passing opportunity.