I got a Rain cape last year , bought from Riv bike right up the road from you..

legs and feet stay pretty dry , because the cape drapes over my arms and the handlebars, forming an awning for the bottom half.

Mudguards are needed , on the bike.

NB poncho, I observe, is a flat square and will flap in the wind.. ,
But cycle rain cape is a conic shape, a bit longer in the front..
and less an issue in the wind..

helmet cover on your helmet, after you put the cape over your head.

parking in the rain I use a heavy plastic bag on the saddle..

the bike dries off when I bring it in, back home