Have you ever been listening to Sleep's 63-minute song "Dopesmoker" and felt like it should be slower and maybe a little longer? YouTuber Zed Edit sure did, and now we've got a version of "Dopesmoker" that's about 5.5 hours long and sounds like a Sunn O))) outtake.
I think the real challenge here is to maintain a consistent level of high throughout the entire track without pushing yourself into a new dimension. Or maybe that's exactly what you should be doing.