Remove/Extend default expiration date

Hello again,

So my classifieds site is free for all, no listing or membership packages. What I would like to do is remove the 30 day default expiry period. Now, I’m using the expiry option in ‘edit listing’ as a way to notify my users when their listing is deleted by marking it as expired, so I would like to keep that but specifically extend the timeframe (let’s say for 1 year) and not have it to show on the listing page. Now I know as an admin I can change the timeframe manually, but I would like to have that set as a default, one year from date of posting for example. When the user views his listing page, it shows the expiry date and that can be worrisome for them, so I’d like that to not show.

Any tips and help is much appreciated!