I think this song has become non-contiguous. The scansion does not fit. I think we should concentrate on who is to perform this song. For example, I imagined the singer of the first line would be an earnest 18-year-old, playing an acoustic guitar. The 2nd line does not quite fit with that image, but the 3rd and 4th lines could. The butterchurn girls, boom bang-a-bang, and keyboard solo and flame sax seem to belong to three different acts. "My little pony" might do for a chorus, although personally I would not vote for that lyric. Personally, I was imagining an earnest 18-year-old, female ingenue with an acoustic guitar, but an 18-year-old lad with a beard would do just as well.
So, the first thing we have to do is work out what sort of act this is.
Well if you are going to go for some inexperienced whippersnapper instead of a