I'd really like to avoid having to visit a US POE in person on the way back if at all possible.
To my knowledge there are only two POEs in the San Juans during the summer/early fall, Friday Harbor and Roche Harbor. We used to be able to clear at Bellingham but I don't believe that has been possible for many years. I don't know about Anacortes.
It sounds like I need the DTOPS sticker for the boat, which I can order on line. I'll do that.
Yes, legally you'll need one. If you clear into the US by phone I think--- but I'm not positive-- that you will always be asked to provide the number of the customs decal on your boat.
For crew (just the 2 of us), is NEXUS the next step? Do we have to go to Canada for a face-to-face?
If you want to clear back into the US by phone you will need a Nexus pass for each person on the boat. The pass requires an in-person interview but you don't have to go to Canada to do it. You can make an appointment in Seattle, for example, for the interview.
However...... I have heard horror stories of how long the wait time can be before you can get an appointment in Seattle. It seems to be much faster to make an appointment for the Blaine border crossing and do the interview there. However I don't believe it's a walk-in situation. You still need to make an appointment.
Is it worth it if I don't cross regularly?
That depends on your situation. For us a stop at Roche Harbor on the way back into the US has so far never been much of an inconvenience. We usually clear the day before we want to be back in Bellingham and spend the night after clearing at some nearby spot in the islands: Parks Bay or Indian Cove if we want to anchor or West Sound if we want a harbor.
However if we were heading home from someplace on the eastern side of the Gulf Islands then it would require a long slog to the southwest to get to Roche Harbor. So in that situation clearing by phone with a Nexus pass would be much more convenient for us. We used to do this with the old Canpass/PIN system, heading straight home from places like Cabbage Cove, Montague, etc.
However in recent years we've always had guests on board for our Gulf Islands trips, either from here or from Europe, and they've never had Nexus passes. So we would have had to clear at a POE no matter what. So we've simply planned our itinerary to be heading back into US waters more from the west: Sidney Spit, Port Browning, Genoa Bay, South Pender Island, etc. So going to Roche doesn't require a side trip and a long backtrack.
Finally, what about the Small Vessel Reporting System (SVRS)?
I know absolutely nothing about that program, I'm afraid.