Extracting parts of an MBTiles file into separate files using custom polygons

Question

I have a planet.mbtiles files and I need to create custom .mbtiles extracts using custom polygon borders and not any form of bounding box. The only two tools that I can find is mbtiles-extracts and tilelive.

• mbtiles-extracts:

  Seems to me the most promising i.t.o. what I need to do, but I cannot get it installed. Probably because I am a newb at nmp and don't quite get the errors when trying to install.

• tilelive:

  Seems to me the most trust-worthy and supported and would rather use it, but it seems I can only do a bounding box extract, but as I said, I need a polygon extract of the planet.mbtiles file.

So my questions are as follows:

Which one of the two should I use to complete the task, and depending on which one to use (probably tilelive), how do I do an extract using custom polygons instead of bounding boxes?

Is there any other way to accomplish my needs? can you please provide suggestions?