There hasn't been a need for something that simplified since WW2, That said you'd be better off just building truck mounted artillery if the cost and time factor was that much of a concern.
I'm sure zebra's with a breeding program like what was done with those foxes could achieve a domesticated zebra but there isn't anything a zebra can really do that a horse couldn't do far better.
Pretty sure that if the US lost a war the way Germany did then someone like Hitler (Who had amazing oratory skill) could easily rise to power and Americans would be foaming at the mouth for revenge too most likely.
Germany is the other who for whatever reason also doesn't have any towed artillery but their military is underfunded. Regardless the lack of towed artillery is just weird given how relatively cheap it is compared to self propelled platforms.
Does anyone know the reason why Poland and other Euro countries seem to have zero towed artillery? Is there a doctrine reason for this I am missing or something?