In mobile home covered skylights...

Have you considered a drop ceiling, a grid is put up and acoustic tiles are put in the grid.

Here's a link of what some people have done to their mobile homes:

https://mobilehomeliving.org/10-materials-to-replace-mobile-home-ceiling/

You could consider putting in what looks like a false "window" a plastic panel with LED lights behind it. The LED last a LONG time and you could put the switch to turn them on on an edge so its not an eye sore.

The LED idea is a great one and they are VERY energy efficient and will bring in the light that you're missing. Another thought is to locate canvas artwork in the same size and attach that into each skylight are or create your own buy painting canvas with a sky and cloud theme. Since you have the additional height, use it to your advantage.

We had that exact issue in my daughter's. We purchased a plastic panel which was surprisingly a perfect match. Here's what we used:

https://www.homedepot.com/p/Glasliner-4-ft-x-8-ft-White-090-FRP-Wall-Board-MFTF12IXA480009600/100389836

Cheapest thing to do would be to paint the ceiling with a pure white paint.

Wrap string lights?

They have very inexpensive LED lights that work on a remote or timer and they are mounted with a sticky tape. You could use those and leave them uncovered or cover them as others have suggested.

I love the idea of string lights (they make everything prettier)!

You can stencil the roof

What about sticking some battery powered lights up in them? You can get some with a remote control to make it easy! :)

Maybe an artificial battery light. Something like this: https://amzn.to/3bLnIer