ERC20 token transfer proxy implementation

Can anyone recommend a proper ERC20 token transfer proxy implementation in solidity? I see it being used in a lot of protocols, 0x for example, but I haven’t ever done it myself and it seems a bit complex just reading their smart contracts.

Basically, I would like to write a contract that’s upgradable. And I would like to designate an ERC20 token transfer proxy that I make my token transfer approvals to. So that when I upgrade my logic contract, I don’t have to re-approve.

If anyone knows of a simple how to, explainer article, or can explain it to me that would be helpful.