Those things might be purple at best. How about an add on that you can traverse to a portal at any time, but it takes longer or when you get out of a portal survivors have an unknown exposed status effect?
I've been thinking about some ideas for ths as well. Would it be too strong if survivors who successfully destroyed a portal would get exposed for x seconds? Similarly to Haunted Grounds, but only for those who worked on the portal. I think the addon should cancel the oblivious effect in that case because the combination of both would be too strong. If that's done, I think this would work for an ultra rare.
That would actually be a good, but not op add on. Risk having the killer come to you or risk having the exposed status effect so you can do the gen safely. The killer would have to get to the portal cleansed for it to work. Id say 30-60 seconds somewhere around