This hurts my heart Just kidding But seriously, I hope you’ll give the SAB a shot before deciding it’s undoable. I’ve poured literally hundreds of plates in a SAB with super minimal contam rates. I wanted to link to some Shroomery threads on this subject but it appears to be down at the moment. So much of this hobby is about experience - take what you hear from hobbyists and try it for yourself.
One thing you could do is use those plastic petris you have to practice your technique. Even if you don’t intend to do transfers, you can pour the plates in the SAB, seal them, and then set them aside to incubate. If your plates are clean after a couple of weeks, then your technique was solid.
When doing transfers, it’s good practice to leave one blank plate aside from each batch. If you end up with contams in your transfer plates, the blank plate will help you to identify when the contams entered the picture (ie. If the blank is still clean, then it’s likely that the contams were introduced during your transfers. If the blank is contaminated, then they were likely introduced during the initial pouring).
Nice! That sounds great. I also thought I should mention that PP5 plastic containers can be sterilised. My local sushi place uses small ones for soy sauce and they’re perfect for agar (and can be reused). You could pre-pour those (they come with snap-on lids). Bigger (PP5) plastic containers work well for grain jars etc.