you could automate this a bit with the API. @jeanphilippeb describes something he made that gets the CV suggestion for a set of observations here: https://forum.inaturalist.org/t/ai-assisted-occurrence-searches/19676. you might be able to adapt his process or write something of your own.
given 50MM RG observations in iNaturalist, a representative sample with 95% confidence and 3% margin of error would require a sample size of at least 1K.
iNaturalist does offer a way to return a random unique set of observations up to n=200 by using &order_by=random. your way works, too, but it may be easier to do this.
UPDATE:
i thought about this a little more, and it may be worth noting that the suggestions you get from computer vision may differ depending on whether the observation already has an ID. based on my reading of the computer vision API logic, the suggestions will be limited to the current iconic taxon of the observation. so an observation that is already identified to, say, birds, should limit its suggestions to only birds, i think. this may be relevant to the design of this investigation, since this means that even using the same CV model, each ID could get different CV results depending on what its observation has been identified as at the time of the new suggestion.