Multisite & SSL

I have a question specific to using Let’s Encrypt certs. Working great for my main domain. Have a Wordpress MU site setup using subdomains on a DH VPS. I found this thread:

Will this work with Let’s Encrypt? To make things a bit more complex, the domain is using GoDaddy’s nameservers. (The client has a ton of DNS records for the domain and doesn’t want to move it, but they got sick of GoDaddy’s terrible hosting, so here we are.)

I have the A record at GoDaddy set to point to my Dreamhost IP (specific to my main domain). I have a Let’s Encrypt cert installed on that domain. I have wildcard DNS setup, so my subdomains are working fine except that they’re not secure (thus throwing the dreaded certificate error). Is there a way for me to leverage the free Let’s Encrypt certs or would I be better to buy a wildcard SSL cert and install it on the domain?