Could you? Probably. Should you? I don’t think it’s a viable long term plan; I think you’re setting yourself up for burnout and I think most specialists would quit the large animal down the line anyway, just from what we see as trends in that field with people leaving it for small animal.
From being an intern who spent 3 months on neuro and being friends with neurologists, neuro seems to be a field with a lot more on call and schedule variability than other specialties. That down back dog needs cut when it needs it, and if you’re away on a “farm call”, they’re gonna go elsewhere. Being a practice owner is practically a part time job itself because of paperwork and people management, and there are only so many hours in the day. Plus who is going to see your ambulatory large animal patient’s emergencies while you’re back doing neuro? If you built a large enough team in both aspects it could maybe work, but if you truly want to do neuro I think you’d be better off specializing and then just trying to make your research interest something large animal and carve out a niche in academia like that or something. I think it would be exceedingly hard to do both in private settings, and especially to try to do both things and being an owner while still doing all three jobs well. Something will have to give eventually.
Also, I know not everything in life is about money and I realize you’re considering the ambulatory stuff as a passion project, but the pay discrepancy is huge. I am a specialist and if I’m gonna work 6-7 days a week, you can bet I’m gonna do so in my specialty field where I can make significant money for the effort and not go work a GP shift where I may make less than half the salary for way physically harder work. But that’s my own opinion, and yours may be different.
But your plan sounds like a recipe for burnout to me. Possible, yes, but probably not realistic.