Two engines, one pushing and one pulling, would appear an obvious solution to keep extra drag down following from more engines. But apart from a few floatplanes it is difficult to find operational examples of the principle being applied - was there a backside? Could the turbulence from the front propeller mean that the second propeller is much less effective? Is there a similar effect from contra rotating propellers?
IIRC the aircraft that have some distance between the front and back prop didn't suffer any notable drop in reap prop efficiency, like with DO 335. Some countries might not like a tricycle landing gear in mid-1930s, but that should not stop a design and manufacture of it - the layout was used already in ww1.
There was also the
Fokker XXIII, a twin-boom A/C, that was supposed to do 326 mph on two 530 HP V12s. The suggested versions with Kestrels, Jumo 210s and HS 12Y didn't materialized, so those should've also been valid proposals if undertaken in time.
Anyway I'm sure that it would only take minor PoDs to produce an engine with 1000+ HP by 1935 - like a gifted engineer with a few good days and some financial support.
There was the RR Buzzard from before 1930, more than 900 HP on 77 oct fuel. The racing spin-off, the RR 'R', was pushed to beyond 2300 HP (using an excotic fuel mix, that included benzole, to allow for greater boost and thus power; also a much bigger S/C was installed to provide that boost).
IMO, a Buzzard running on 87 oct fuel would've been easily above 1000 HP.