I agree a look at the tram subway ramp would be good. People won't
have seen conduit tram tracks before.

Stating the obvious again:

a. that's c.5 mins walk from the LT Museum (if only to know where it
is) and
b. offers Covent Garden Market as "site" other than transport (and
possible watering hole/loo stop)
c and if urinals are an attraction it's only a few minutes further
to Charing Cross Station for the Butterfly urinal, and possibly the
pop-up urinals outside Embankment Station although I doubt they'll be
out to play early enough for you.
--
Robin
reply to address is (meant to be) valid