I made a 3d printable eReader case for my wife. Wanted to test what would happen if we water logged them and left them in the sun to dry.
Two of the cases are made from PLA while the other is made from PETG. They are all held together by thread and leather.
The test here is to see if moving from PLA to PETG was the right move since the last time I did this, the case turned into a banana.
My eventual plan once I’ve finished with my testing is to sell these cases and make their designs available for others to print.
I don’t think your particular case would have any creep as it’s not mechanically leveraged in any real way.
If you were to print something like a cupholder for a stroller or bike where it’s holding something up with some weight while in the heat is where you would notice it especially with repeated impact. Most likely wouldn’t outright fail but under constant load you would notice it starting to bend a little. That said you can absolutely over engineer it to prevent that rather than switching materials which can be a huge pain depending on the printer.
I did my hydroponic tower in PETG but it honestly would’ve been ok in PLA since it’s just a static fixture. I’ve had a PLA badge on my car for 3 years in 110+ summers and similar to you I’ve only noticed fading on the raised white lettering.