I don't think there is any other option. If those are very simple websites, there are some wp plugins that allow you to map them to domains, i.e you can use a s

I don't think there is any other option. If those are very simple websites, there are some wp plugins that allow you to map them to domains, i.e you can use a single instance of WordPress and map the content to different domains. One plugin for this use case is WP Landing Kit.