Expiring a funded logic sig

Want to create a funded logicsig and then return the funds to the funding account if the logicsig funds have not been taken, after a period of time.

Seems that HTLC needs to know who the funds are ultimately intended for, and my use case is that the ultimate recipient is not known at time of logicsig/htlc creation.

Any tips appreciated on how to handle the above?

Note that in this case you necessarily need to have a trusted party store a secret key.
Indeed, otherwise anyone could steal the funds as soon as the contract expires.

The simplest solution is therefore to just have the trusted party generate a target account and use this target account.

Remark that from a security point of view this is the best you can do.
You can use other solutions based on Using a Smart Contract for Advanced Approvals: Hierarchical Thresholds | Algorand Developer Portal
But if your trusted party uses a single secret key or a multisig, the above ideas would not provide any additional security.
Indeed, the trusted party can always steal the funds! (That is why they need to be trusted)