I would give it a shot at the border. You WILL be allowed into the country, as you are still a PR. You have that right.
The question is if you get reported or not.
If reported then you will be given paperwork to say as such. You have 30 days to appeal. As mentioned, this can take up to 1-2 years, with you living and working in Canada in the meantime. However if you don't have good reasons, such as H&C, which it doesn't sound like you do, then you will lose that appeal and have to leave.
If you don't want to appeal then you can simply renounce your PR and then leave within the 30 days.
If you did decide to renounce your PR then you can always apply again via express entry. There's really nothing to lose by trying at the border.
If you are lucky and do not get reported, then you must stay in Canada for at least two years to meet your residency obligation. Only after that 2 year period has comfortably passed should you then apply for a new PR card. I'm not sure about your access to healthcare, others will point you in the right direction.
Your SIN will allow you to work, and as already posted, there are ways to make this no longer dormant.
Good luck and please do let us know how you get on.