Not expert, just naive for any kind of insecure network, especially The Internet!
End-to-End Encryption tunnels, like HTTPS and VPN, are the only sane way to use an insecure network, these prevent Man-in-the-Middle sniffing/modification of POSTed content, requests and responses, by any intermediary, including ISPs, routing parties, governments and employers, and this sniffing/modification behaviour has already happened loads! HTTPS certs also make it easier to spot spoof sites e.g. via DNS exploits. HTTPS is especially critical for all links to third party sites e.g. scripts, fonts, media etc.! This is why ALL websites, even seemingly trivial ones, must be moved to HTTPS.
HTTPS certs can be obtained free and there are scripts available to auto-renew short-lived HTTPS certs.
If you really need caching, put HTTP cache(s) between main HTTP server(s) and HTTPS front end(s), all on an isolated network.
Biting the hand that feeds IT
