@tehmoon, this was discussed before at
Unfortunately there is only one reply in that thread, but maybe it will have some ideas for you.
Distributing the private key corresponding to the subject public key is forbidden by the Let's Encrypt subscriber agreement, even if you don't distribute the account key. The private key corresponding to the subject key can also be used by itself to perform revocation. While it's not clear that someone would succeed in revoking your certificate every time if you made a new one every day, having a routine, automated violation of your subscriber agreement is not a good idea to rely on.
I think it would be interesting to hear what browser vendors think about HTTPS for localhost, and maybe we could try to get ahold of some of them and get them to comment here.