Spirit gum would work, but not all day. It will also turn white when you sweat on it, so maybe not the best choice for the palm.
I would suggest a glue called Pros-aide. You have to let it pretty much dry on the skin, and have some on the wonderflex too also let it turn clear, then stick them together, powder anywhere that has glue and is not in between hand and piece and you should be good to go!
This is my favorite type of glue for pretty much any prosthetic.. or gluing things when doing make up in general.
You will need a remover for it though. They sell actual removers, but its cheaper to just get isopropyl myristate. Where ever you buy pros-aide you should be able to get it.
*Is actually a professional make up artist*
Currently working on:
Nausicaa- Nausicaa of the Vally of the Wind
Dark phoenix- x-men
Azula-Avatar the Last Airbender