My understanding is that at least some of the various proposals to 'do something' about the railway to Charing Cross/Hungerford Bridge (none of which, AIUI, originated from the railway) were worked up to reasonably detailed published proposals (including outline plans), and one or two into the authorisation pipeline, but I don't know how far.
There is a chapter in a book (I forget which one) on the Southern Railway 'How Sir Herbert [Walker] held the bridge' on the subject of the 1920s-30s proposals...