It is not so bad at all. In a first step you can replace your client.print with message += and set up the handle functions for the different pages and endpoints. Reading of parameters will get much easier. Overall I think your sketch will get even shorter.
Your planned "workaround" doesn't make so much sense for me as there are real solutions to your problem which were already shown to you.
Thanks, noiasca, I'm sure you are correct, but it's never that simple for the unwashed (me).
Although I think I remember using the ESP8266WebServer/HTTPWebServer in a project many years ago. I didn't use it because I was smart, I simply found an example sketch that was easily modified for my application.
I'll see if I can find that sketch and get re-acquainted with it and go-forward from there.
Thanks, again,
Frank