Load Balance with SNI Question

From the excellent article here

I have used this technique for years now, but i wonder would it be possible to dynamically use subdomain (from example linked) - as poart for naming the the backend connection with some kind of variable, the reason i ask is because i have 400 subdomains (and backends)… and growing

So ie. some way of making this connection below dynamic - by using the “application1” part in a some variable? - i have tried back and forth - but i don’t get it to work

acl application req_ssl_sni -i application1.domain.com

use_backend bk_ssl_application1 if application