Hi @slfdr,
First of all, I suggest looking at Points to consider when creating a fungible token (ERC20, ERC777)
Tokens should be appropriately tested and audited, along with ensuring regulatory compliance.
A deflationary token can cause issues such as this recent issue: https://medium.com/balancer-protocol/incident-with-non-standard-erc20-deflationary-tokens-95a0f6d46dea
We can’t add functionality to a smart contract that isn’t upgradeable. So as you suggested you would need to redeploy.
Happy to point you in the right direction but you would need to write and test the contract yourself.
If you are looking for a smart contract developer, you could post what you are looking for in the community forum along with what you are offering (such as payment) to see if there is anyone interested in the community.