Thanks for pointing that out.
The message I posted (3 or 4 above) has an attached document (Standards Chart SSG.pdf) which is currently available on the USYS website. It clearly says that 47x30 is the maximum field size. The document that you are probably referring to is currently available on the Cal South website (USSF_SSG_Chart_080416.pdf attached below) which lists that as a minimum. Some ambiguity there, but I suspect that the USYS document has a typo and it should read "Minimum Field Size" for 47x30. The document available on Cal South says "Revised 11/23/15: 7v7 field range corrected to reflect accurate field dimensions" at the bottom, so would appear they caught and corrected the mistake, but USYS still hasn't updated the document on their site.
Nobody that is complaining about Surf Cup 7v7 field sizes has yet posted what they actually were. In situations where I've felt that a field was sub-standard, I've paced the lines to determine the approximate distances. Hopefully someone that is complaining about the field size felt strongly enough to actually validate their opinions.
I'd say that if the fields in question were near the Cal-South minimum, they have a valid complaint. This tournament advertises itself and is perceived to be a high standard competition. Using the minimum standard field, if that is actually the case, is not in keeping with that ideal.