Question: why not just tune it lower vs. have derived suboctaves (as discussed above)?
BTW from producerdojo.com I learned an interesting technique which is basically distorted sine sub bass. Step 1: have a pure sine tuned to your sub frequency, which gives you a very controlled and very powerful fundamental. Step 2: mult that to another pathway, distort the hell out of it to taste, highpass filter it so you can add it on top of your pure sub without problems, and do other filtering plus leveling for control to taste. The results are i) you get a powerful controled sub ii) you get a fizzy or nasty top you can mix in to taste iii) you can CV or otherwise change the top for lots of expression / variety iv) everything tracks pitch, gliss and dives perfectly. I've done this in VSTs but not yet my eurorack setup, should work fine in eurorack.
If the clock divider technique (from above) works well, I'll need to add that to my box of tricks and try it in eurorack soon!