It would be quite surprising to me if your idea did not work out, simply because doing good for animals via donations tends to be really low cost (but might depend on what “a lot more money” really means in your case). Imagining for instance that for each and every restaurant in the world some non-negligible cut of the rent (say 5%) would go into effective animal charity, my super rough 3 minute Fermi estimate says that would amount to something in the order of $10 billion per year. Given that about 80 billion land animals are slaughtered each year, that would mean that at a cost effectiveness of sparing 8 animal lives per dollar donated (which doesn’t sound entirely unrealistic), your suggested approach to leasing to restaurants would, on a global scale, not only be net positive, but very theoretically end factory farming of land animals (obviously not in practice given diminishing marginal returns). It’s a very hypothetical argument, but maybe it adds something.
Apart from that, maybe there’s a way to attract more vegetarian/vegan restaurants in particular? No idea about the concrete processes and legislature around that, but maybe you have some power in that regard.