Trial chamber - spawn via ancient city portal

The addition of the trial chambers sounds great. However, it gets harder and harder for long term worlds to reach unexplored chunks. To solve this, the trial chambers should be able spawn in already explored chunks which could be done by using the portals in ancient cities. If you have already planned a use for those portals, why not allow modifications to the ac portals to reach different dimension. For example, chiseled copper blocks could be used to cover the reinforced deep slate on the side that faces the inside of the portal and the then covered portal could be lit like the nether portal.