SDF has a VPN service currently with endpoints in the USA and in Canada. More are on test and hopefully coming soon. The tutorial is a little out of date wrt setups https://sdf.org/?tutorials/VPN

Well there are some Doug Demaw books on scribd.com which might be of appropriate vintage ( QRP classics or W1FB Design Notebook for example ). Maybe search ‘QRP’ in the books section of archive.org but I’m not so confident on that one.