Cloudflare proxy with authoritative zone in Route53

[ngraef]

My team is currently using external-dns with the Route53 provider. We're looking into using Cloudflare WAF with a CNAME setup while keeping the authoritative DNS zones in Route53. As far as I know, it's not possible to have a wildcard record that points all subdomains to Cloudflare, so we'd have to maintain records in both providers:

Route53
www.example.com CNAME www.example.com.cdn.cloudflare.net

Cloudflare (proxy)
www.example.com CNAME abc.us-west-2.elb.amazonaws.com

I know we can run multiple instances of external-dns with different settings for different providers, but I haven't figured out how to automatically create the CDN CNAMEs in Route53. Is there a way both records can be created from the same Service/Ingress? Or would we have to create an ExternalName Service alongside each resource to handle the Route53 records?

And on a more opinionated note: is this a terrible idea? Should I just move the authoritative DNS to Cloudflare?