That's a great solution, Avior! You could even bring it to market!
My favorite cupholders of all time were ones like these:
https://www.michiganmotorz.com/seachoice-folding-adjustable-drink-holder-black-p-10641.html?gclid=EAIaIQobChMIyIfisJ7s4QIV2FqGCh3hU QaVEAQYAiABEgK6I_D_BwE
I haven't tired them in my Boxster, but they worked great in my 87 Dodge Radier! They can be mounted various ways, but I just screwed them into the door cards. Damn I miss that Raider!