Is there a way to make only a shell mesh and retopologize it?

Hello blender friends,

I want to paint on the object surface with a clean front/back UV, so my idea is to find a way to make a shell of it and retopologize it. Or I can use the original UV and retopologize it within the shape of it. but I’m not sure if either of the ways work and how to do those. Is there a way or better idea to do it?

Also, I want to separate the bottom from the others cuz it always stretch, but I don’t know a clean way to do it :frowning:

Huge thanks to you guys in advance!

Here’s the image of the object I’m using:

make a low medium poly with retopo to get a clean mesh

then you can use texture painting to paint on UV of the low poly model

happy bl