Take a look at OCSP Stapling which was created to mitigate the problem of OCSP responder being down or unavailable.
the certificate holder (the web server) queries the OCSP server themselves at regular intervals, obtaining a signed time-stamped OCSP response. When the site's visitors attempt to connect to the site, this response is included ("stapled") with the TLS/SSL handshake via the Certificate Status Request extension response
All major browsers and web servers support OCSP stapling.
As far having the OCSP responder check the CRL list, this is technically possible but might lead to performance issues if your CRL list gets very large. Ideally you would want your CRL list to be stored in an indexed database of some sort which can be queried efficiently by your OCSP responder.
Instead of rolling your own OCSP responder, it would be better to use a proven existing responder which can check against a an indexed database that contains your CRL list entries.