Thinking about breeding plecos, have questions.

BN are probably the easiest to breed, definitely a good starting point. You can keep more than one male in a 4' tank, but the females aren't likely to spawn with more than one male unless you use a divider to separate them. They're fine as pairs or trios for breeding.
I keep L-333's in a 30 long with my BN breeders, no problems. The Hypancistrus are much slower to grow/mature than Ancistrus species, the BN have been breeding for months while the L-333's are apparently still not old enough. (The L-333's have been in the tank longer than the BN, and were larger juvies when they arrived than the BN that wre added later.)
The Peckoltia's are faster-growing than Hypancistrus, I have a group of L-134's in another tank that will likely be spawning sooner than the L-333's.
I find sand substrate better for pleco's, food doesn't get lost like it does among pea gravel. I also have loads of fast-growing plants (Najas, hornwort, duckweed, and/or Amazon frogbit) in my breeding and growout tanks to help with water quality between partials.

Good information! Thank you!!

You won't need to divide the tank to separate different species. It may not even be necessary for BN if you don't plan to keep more than a pair or trio for breeding. I wouldn't keep more than 2 females with one male though, they don't leave the cave while they have eggs or fry to tend. One male could probably breed with more than 2 females, but he'd never get a break between spawns.

I personally would take a chance to test that theory that adult male bristlenoses will kill another adult bristlenose when they are mature enough to spawn. I had two males in m 75G, one matured faster than the other and began to breed first. A few months later when the second male showed signs of breeding maturity, it seemed he started to harass the first male in a cocky sort of way. Hung around male #1's cave, cruised in and around that cave just a little too much to suit me. So before they got a chance to get into a death fight, I separated them. Up until that point, all the ladies that were mature enough to spawn had selected male #1. I moved male #2 into a 55G and selected two females to be with him. Meanwhile all my mature females in the 75G were ready to spawn at just about the same time.....so with that, one by one five females went into the cave with male #1, until there were 5 egg batches inside the cave. In five separate spots in the back. All I can say is thank goodness it was a first time (unfertile) spawn for a couple of those females!!

My tanks are heavily planted, low tech, with round river gravel substrate, with large pieces of malaysian driftwood. I also supply the male with a clay spawning cave with the opening to the front of the tank where I can see what's going on.

Getting 4-6 and growing them out to see what sexes they are is the best way to go.