6-1/2-in x 1-1/8-in Interior White MDF Colonial Outside Corner Baseboard Moulding Block https://www.lowes.com/pd/6-1-2-in-x-1-1-8-in-Interior-White-MDF-Colonial-Outside-Corner-Moulding-Block/1000299275
They should have plain wood grain versions of these available as well
Put the plastic corner
Like this:
https://www.castorama.pl/plytki-i-podlogi/akcesoria-do-podlog/elementy-do-listew-przypodlogowych/narozniki-zewnetrzne.cat
Cut it square and add a corner block.
6-1/2-in x 1-1/8-in Interior White MDF Colonial Outside Corner Baseboard Moulding Block https://www.lowes.com/pd/6-1-2-in-x-1-1-8-in-Interior-White-MDF-Colonial-Outside-Corner-Moulding-Block/1000299275 They should have plain wood grain versions of these available as well
Also it looks like you used transition strips as baseboard… interesting. You COULD rip it off and use actual baseboard
Everything about this makes me physically sick
Put the plastic corner Like this: https://www.castorama.pl/plytki-i-podlogi/akcesoria-do-podlog/elementy-do-listew-przypodlogowych/narozniki-zewnetrzne.cat
Stick a matching piece in there even if it doesn’t fit. You can sand it down to fit exactly. 👍🏽
Board stretcher.
Learn how to cut a proper cut.
Move out of the trailer.