In case anyone would like to see the reckless code that constructed these weird transactions, here you go: https://gist.github.com/VzxPLnHqr/acc4fd4ee399196e7723a7d36a90834b#file-pay2sig-sc

Building little custom transactions like this has taught me a lot and made it clearer as to why some constructions are not possible (such as due to a hash-cycle), or possible but insecure, such as the weird ones presented here.

Maybe somebody will come along and figure out how to derive the next public key such that they can sweep the remaining sats in that address!