Ways to make seat softer, add more padding?

I am starting to notice a small decline in the softness thickness of the padding on the front drivers seat. I have the II model no options. The biggest area is where my lower back(around where my belt touches the lower seat back) only has a little bit of padding left then i can feel the hard surface behind it.

Do you have ideas on how to make the seat softer? I would like to do something before the end of the year cause i have a 16 hour trip to MI.

I'm thinking i can lay something over the seat, maybe a memorey foam pad or something like that.

Do any of you guys use anything that helps? thanks in advance.

 

I'm trying to hear ideas from anyone. I'm poor so i can't afford to spend to much. but would like to find a way to make the seat have more padding, in a way that wouldn't move around when i get in and out. I haven't been able to find any padded seat covers, just cheap seat pads.