The wavelength of 1512 kHz is 198.3 metres, so a quarter wavelength will be ~49.5 metres.
If he got 50 metres of wire and put it over the side of a high building, and tied off the lower end to the top of a lamp post (or anything else well above head height) with an insulating string (we used to use nylon fishing line) so that the aerial was about 15° out from the building, and then earthed the rig to the building's lightning conductor, he'd have a big "Inverted V" aerial, with a match at about 50Ω!
You'd be surprised at how far you can get on AM with a relatively low power. At one time we ran just 8 Watts carrier and ~30 Watts peak, and got daytime coverage of much of London and surrounding areas!
My current experimental rig runs around 1 kW PEP (250 W carrier), and I've found a site that will allow a big enough aerial for operation towards the lower end of the band..... A brief test into a non-ideal "Marconi" aerial resulted in signals audible throughout the Benelux in the daytime (though not "entertainment quality"). With the big aerial rigged, and a quiet frequency (now that most of the Medium Wave stations have disappeared), I should be able to get quite spectacular coverage.....