One time you talked about a "reasonability zone" of tempos between 60 and 120 bpm and neither of these tempos is in that zone so I think this is sort of An exception to that rule. Thoughts?
if you put it in 6/8, the size of the bars will be within that reasonability zone (between 2 and 4 seconds per bar). you can also do it either of the 2 ways you tried it, if you don't mind the bars going by really fast or really slow