He just needs to get it working first, then he can play around with making larger/higher quality proxy files… and H.264 is just a container. you can create any compression/quality that you want with including leaving out delta frames for low cpu usage.
This is all just a misconception of the technology. plus if he doesn’t have a lot of space, the proxies could take up most of his drive. Not everyone does this professionally so they may not have the ability to playback larger bitrate codecs because of the hard drive transfer speed limitations.
I would personally prefer Cineform Wavelet compression as it uses less cpu overhead compared to older DCT codecs(H.264 is DCT like both Prores and DnxHD) and has less artifacts. H.264 just got a bad rep because everyone added millions of delta frames and forgot they were optional. In many cases, it can look better than other codecs at similar sizes/bitrates, even at 10 bit. Main 10 is also supported.