Transgenic plants with multiple genes?

I have in mind, as a hypothetical project, to generate a transgenic plant capable of synthesizing vitamin B12. This could be consumed by vegans, for instance, as an alternative to B12 supplements or provide B12 to those that are deficient of it, since this vitamin can only be aquired by consuming animal-based products.

However, after researching a bit, I found out that this vitamin needs at least 30 enzymes for its complete biosynthesis in bacteria. At least 5 of them are already present in plants (the first steps of B12 to siroheme, which is a cofactor also synthesized in plants). The rest of the enzymes (around 20) are only present in bacteria.

Is it possible to make a plasmid containing 20 different gene constructs and transfect it via Agrobacterium transformation? Although I know that plasmids have limited space, so maybe I could use different plasmids, each one with different selection markers?

Thanks in advance.