To be honest, I'm not convinced of the banana routine. I tried it a few years ago as an experiment. Two toms, same variety, same degree of ripeness. One in a bag with a banana, the other one au naturel. There was little difference in the outcome.
But if the banana were to be tried, it needs to be in the confines of something like a bag with the tomato in order to maximise the effect of any ethlyene gas. Otherwise it just wafts into the atmosphere.
Flowergirl4 has suggested uprooting the whole plant & hanging them upside down, after watching Chris Beardshaw in the 'how to' section of this site. I have watched it, and it would appear to be a well tested route, having been suggested by an expert. I don't think my 4 plants will produce many fruits now that September is here, even though I still have many flowers at or near the tops. If I were to try that method, is it best to do it now, or wait a little longer?