You're tripping yourself up by creating a pretend "Singles" album, which isn't really an album at all, because it will be hard to make it behave like one.
As you have already discovered, if you sort by year and the year values are different, there is no way to then have those tracks grouped together.
You could store two year values, one for the album and one for the track - the Original Year tag might come in useful here - and then sort on the Album year to stop the tracks being separated.
Another possibility is to create a new Virtual Tag and sort on that instead.
Use a formula to check if the Album title is "Singles", and in that case substitute a different date to sort on instead of the one in the Date tag. It's up to you what this would be, but as you aren't displaying the year in this view, you could use something like '0001' purely for sorting purposes which would display your Singles before other album releases.
Sorry, I don't have time to include full examples, but hopefully this helps with other ways to think about the layout.
Bee excellent to each other...