Killers: Twilight Zone was another non album track, and judging by the recent WOTW promotion, Maiden consider Purgatory as the first and therefore only single off Killers.
FOTD: Wasting Love was the third single in a lot of territories.
You're missing out a few things inbetween. First, SSOASS had three singles. I know The Clairvoyant is a live recording, and it is thus an anomaly in the Maiden catalogue as a live single without a corresponding live album, but it was nevertheless very much part of the SSOASS cycle. It was released only three months after The Evil That Men Do, which itself was released four months after the album. The single artwork also ties in with the SSOASS concept. It has nothing to do with Maiden England or the Infinite Dreams single, which came out a whole year later. Maiden England is also an oddity, first because it only had one single (Infinite Dreams) and second because it wasn't a proper live album when first released, but a video only.
Also I seem to remember that there was supposed to be a Tailgunner single that was scrapped.
V XI - Futureal was again a watered down release, onto 1 format only and only available by mail order
Indeed a weird one. There is no proper release date and it wasn't eligible for the charts either.
DOD - 3 singles from DOD, Wildest Dreams, Rainmaker and No More Lies
No More Lies wasn't promoted as a single but as a "souvenir EP" and supposedly only had limited release. It was even released after the end of the tour.
There are also the cases of the Number of the Beast and Trooper singles from 2005 which weren't really tied to any release. I mean, they were clearly tie-ins to the Early Days DVD and tour, but they were released quite a while after the DVD and the Trooper single came out two weeks before the tour ended, so I don't really think it could be regarded as promoting it.
Empire of the Clouds had a real single
Can you really call it that? It was a record-store day exclusive LP that had no wider release.