Plumbing – How to repair the cracked shower pan

My shower pan, made of gel-coated fiber glass, has three cracks, as shown in the photo below. The cracks radiate fairly straight from the drain in the center at twelve, four, and eight o'clock. (All of the other white streaks are just gel-coat coloring.)

I ground away the cracks and filled them with epoxy, which seems to work okay for the time being. But I would like to know what my options are for a more permanent fix that won't significantly reduce the value.

Replacing the pan is the last thing I want to do. The pan matches the shower walls and a whirlpool bath. A lot of things would have to come out to get to the pan, and I can't imagine a matching pan replacement would be found.

I saw a video where someone had what appeared to be a process for this kind of repair. This involved what looked like an epoxied sheet that covers the entire pan bottom on the top side. I don't know what this is called and I don't know what kind of tradesman I should contact to do this sort of fix. (It doesn't seem like something that a plumber/pipe-fitter type would specialize in.) If someone can point me in the right direction for this, I would appreciate it.

Any other ideas on what I can do and what is common for addressing this sort of problem would be appreciated.

The shower is on the second floor and there is some water damage to the ceiling below. As I walk around the shower pan, I can hear some creaking, and I assume this will lead to flexing and open the cracks up again. I may need to resolve that, too, in the final fix. Does anyone have any suggestions about this?

Also, help with the tags would be appreciated.

Update

From what I have seen in the answers and comments, I need to seriously reconsider how I might remove the pan from the top, remove the subfloor, mitigate any water damage between the subfloor and ceiling below, then rebuild in reverse.

I need to understand how the pan is seated, so I have to examine the situation a little more. But I may be able (with some risk of damage) to remove the shower wall on the shower-head side and remove the short wall under the seat at the other end. Remove the glass enclosure (I did this once before, but I did a hell of a job gluing it back together 🙁 )Without removing the wall opposite the glass door, I might be able to lift the pan out carefully. I have to disengage the drain first, and I don't know how that attaches to the pan. (Do I need to open up the ceiling below so I can get to it from there?)

This sounds complicated mostly because I'm guessing how it's all put together and how things are fastened to each other.

My goal would be to repair the pan rather than replace it.

Putting it back together, I suppose I can strengthen the pan with fiberglass on the bottom. As for dealing with irregularities that could cause it to rock, isn't there something I can bed the pan onto the subfloor with?