I think the issue is more about what to do with the water splashing about when it falls down to the sump? There isn't a way to have it return down a piece of tubing or pipe. Unless you make one.
Which sea clone do you have? IIRC, the 150 is just about 19" tall, No?
If your ok with the splashing water you will then suffer loss of performance due to the head height imposed on the pump. When the unit is used as a HOB the pump doesn't see much head pressure. If you place it in 6" of water, you now have much more head pressure causing less suction on the air intake. Though I can't really say if it will be enough of a reduction to hinder the performance of the skimmer.