The Strait of Georgia and beyond is also our cruising grounds. Stern ties are very commonplace, you would be hard pressed cruising here without performing these at regular intervals.
500' of line is not too much. The idea is that you loop it around something stout and bring the bitter end back to the boat. This way you can clear out fast in an emergency without losing your line, or quietly with less hassle.
I have the willing help of my 10 year old son to go in and take care of things when we arrive, but often I do it alone too. I would hesitate leaving the engine in gear while gone from the boat, but I have considered it now and then. Never had the guts though.
When there's very little swinging room or a bit of wind or nobody around to help, I drop the anchor, set it securely in reverse then pull up enough rode again to bring the boat out in the middle of the cove, almost straight on top of the anchor. She will now swing very little, but should not drag unless there's a lot of wind. Having all the line flaked out neatly prior to coming in, or stored on a stern hung drum is part of the drill.
Often the shore anchor (tree, old wire, rusted ring) will provide too much friction to row the line back out without pulling it through on shore. Again here it's a good idea to be neat and clean with your rope work: Flake it out in the dinghy with the right end coming out the top of the stack. Flaking it on shore will almost certainly catch it on barnacles, branches, oysterbeds, what not, when rowing back.
Be calm and careful, thinking it all through. We have seen (and personally been guilty of) many botched maneuvers with lots of shouting and noisy motor use, risking to suck lines in the prop or worse.
Polypro line will float and cost less, so it might be a good choice for the stern tie. Some of the better ones are also decent to work with, while the cheap, loosely braided stuff is a major PITA.
Good luck on your trip (which probably is well underway by now?)