We kinda already have a Wapeach in the form of Terrormisu in Wario Master of Disguise. Her whole appearance and boss battle is a parody of Super Princess Peach on the same console:
My opinion is hence the same, we shouldn't add more spinoff filler and should make use of the actual Wario series characters that fill the relevant roles.
Terrormisu
Terrormisu, also known by her human name Tiaramisu, is the true main antagonist and final boss of Wario: Master of Disguise. She is an ancient demoness whose name is derived from "tiramisu", an Italian dessert.
www.mariowiki.com
My opinion is hence the same, we shouldn't add more spinoff filler and should make use of the actual Wario series characters that fill the relevant roles.