Whilst I have not actually spawned L134 they are cave spawners just like L46 and other hypancistrus and respond to the same spawning triggers. I would be inclined to say that you are more likely to suceed in a species only tank. I doubt that tank size is likely to be a governing factor so long as the tank is not too small. A three foot tank would be the minimum size but that would be dependant on how large the colony is. I'm an advocate of keeping fish in large tanks due to the more stable water parameters that a larger body of water provides. However in this instance I think it may prove to be too much work when it comes to simulating rainy seasons in a 1000ltr tank. You would be changing a lot of water in a tank that size in order to drop the temperature by a significant amount.
Just my thoughts on the subject. Congrats on your spawning success to date and good luck with the future projects.