Btw don’t be satisfied with black bars, I’ve been using game specific art bezels from thebezelproject on my RP3+ and widescreen hacks when available.
I’m a bit picky with widescreen hacks because some games can get really janky out the 4:3 boundary (particularly with GameCube) and I am too easily distracted by it. I am super intrigued by the bezel project, though. I’m going to look into this now. Thanks for mentioning it.