There isn't a way based on how the map layers are coded, we worked around this on our server by tweaking the spawns timers. We allow for more spawns to spawn more frequently, but to keep the lag down, we only allow them to stay for a hour.

Best advice I can give on this one is to download "Awesome Teleporters" mod and play it that way. Otherwise, you will miss out on a few for sure.

Or just build a outpost in each realm and fast travel to said outpost when needed. True you would have to have a tames and gear in each outpost, but you dont need the runestones to get there. And it cost nothing to go back to the mainland with whatever you are carrying.