Hi

You make the above statement sound like a COC is not needed for a low cost house installation - As far as I am aware, no supply authority" will install and connect supply to a dwelling unless a coc has been issued.To Issue a COC you need to have protection and all the other bits to fill in.
Low cost houses normally have ready boards installed with circuit breaker protection , sockets etc

Then there is the OHSA that states "every user or lessor of an electrical installation , as the case may be , shall have a valid certificate of compliance "

Before the question on a caravan came up and further to reading the regulations I was always under the impression that a caravan would be treated as a portable/fixed appliance. With reading SANS 10142 I have now changed that thought to maybe a COC is a requirement for a caravan , and maybe the caravan park owner would be entitled to request the COC.
Since you have no idea what size supply the caravan park is going to have per site I would think you need to have protection on the circuits.That would be the only reason I would install a DB.

I can only find reasons as to why I would need to produce the certificate and no regulation or interpretation to absolve me from providing the COC - if I was that caravan owner.