When there are more gallons you can safely for more axolotls. I would say bakers racks with half full twenty longs can hold 3 axolotls (one male two females) for good breeding space usage. Depends on what you're using, but even my small three tier chrome racks usually hold well over 200 pounds. I had two full twenties and two fives on them, and larger chrome racks hold even more. They're cheap too. Home built wood racks are easy to find on Craigslist and you can test the weight before you trust water in them. I'd say if you really want to be economical you can potentially have two adults in tens, but 3 in a twenty would much better. A lot of people also just do large ponds. I believe you can get a 120-200 gallon turtle pond or kiddy pool pretty cheap for when they're adults.
For 2 1/2 inch axolotls you can you small sterilite containers until they're big enough. I grew mine to five inches in containers, then put them together in tanks. Cannibalism didn't happen for me in 2 in one sterilite container as long as they were all well fed.
You have a lot of options, but yes, bakers racks will work for sure. The ten gallon to one axolotl rule is flexible once there are more gallons, and especially if you're doing water changes often. I have 7 in a cycled 40 breeder and I have no issues whatsoever with space or water quality since I do changes frequently anyway. I have so many hides I hardly ever see mine, too.
You'll really just have to see how much weight the racks can hold.
By the way, do you use bins, tanks, or wood enclosures for your breeding beardies? Do you keep them separately or in groups? Wondering what your methods were, since they vary so much between breeders. I see a lot around here that keep harem groups in large wood enclosures - one male to three females- but I've seen other styles.