Is object loading set to maximum in your settings? There is still a hard cap on object loading but it will help you reach that cap before anything disappears.

The other thing you can do is get as close as you can to where you think the hunt is and it will usually keep the objects closest to you loaded.

Once it's loaded, you could try making it your focus target so the game has a harder time unloading it. I'm not sure if that helps but it's something to try.