For any or all of your plans, with a Let's Encrypt certificate, do you use the SSLCertificateChainFile directive or append the relevant intermediate certificate to the server/domain certificate so that the client receives the intermediate certificates?
My reason for asking is I use Firefox which newly installed only includes the root X1 & X2 certificates and throws a wobbly if the server doesn't send the intermediate(s), or connects but issues a warning if the intermediate is user imported.
Usage over time will probably find the intermediates installed from other sites which send the complete chain, but I'd like it to work correctly first time.