but do you think a 25 pound wheel would be large enough to accomplish it?
For what term maturation? I think the best practice assuming you can control affinage is about a 6x6 cylinder for a 12-14 month maturation, if you want a decent rind, and cheese with good paste. Assume 25-28% water loss at 85-88% RH over 12-14 months, if you're watching the MFFB. So 25 lbs is definitely enough with a good cylinder. If you're doing an alpine/gruyere shape, then you can still do it, but up the MFFB by a tad, but also keep the room more humid.
I've been trying to talk the owner into letting me do a grana, but he doesn't want to have to hold onto the cheese that long.
IMHO, hard sell. You're competing with real parmiggiano at $10/lb when on sale. Unless you did grass fed/organic grana clone using whey starters for the marketing angle, then you could do $25 ish/lb retail at 16 months. Hard market for parm.
1 wheel (gouda) a month for the purpose of ageing for 18 months.
Nice. Hard there, too, because there's so much competition from specialties like Old Amsterdam and great domestics like Marieke. Are you using classic undefined strain DL culture to get that complex amino acid profile? Makes for some amazing cheese right at 14-24 months. If you're doing gouda, I would do the classic Dutch rindless system to reduce waste. Not sure what a rind would accomplish? Maybe if you did an adjuncted gouda with 35% MFFB and washed it with a morge, that would make for a fun rind. I've done ones like that (pediolacti, helveticus, acidophilus adjunct) for some really tasty and fairly unique flavor profiles.