If I understand correctly, then I can continue using the Rank Math XML, I’ll just add the sitemaps I want Crawler to execute inside my XML.
Not at all, but almost. ?? You can continue using Rank Math without changing anything. If you modify the sitemap generated by Rank Math it will be overwritten by Rank Math next time if something is updated, so leave it as it is.
What you have to do is to generate a custom sitemap file with your 2 CPT like shown above. The next is to generate a index sitemap that contains the URLS to Rank Math XML and your custom XML file like this.
<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="https://www.sitemaps.org/schemas/sitemap/0.9">
<sitemap>
<loc>https://www.domain.com/your_default_sitemap_generated_by_RankMath.xml</loc>
<lastmod>2022-04-30T08:15:26+00:00</lastmod>
</sitemap>
<sitemap>
<loc>https://www.domain.com/your_custom.xml</loc>
<lastmod>2022-04-30T08:15:26+00:00</lastmod>
</sitemap>
</sitemapindex>
Name this sitemap sitemap_index.xml and add this sitemap to the crawler. That’s it.