Humptydumpty, you've said it, " where are all the customs officers coming from ". You might well ask. My D works for a security firm handling sailings from Birkenhead to Belfast. The hours she works are horrendous because nobody wants to do the job/s. It'll be the same in Dover only worse.
Nobody is willing to get up at 4am for the measly wages that are being paid for a job which has responsibilities of safely loading/unloading passengers,security checks can only be done randomly because of staff shortage and this includes passengers and cabins of vehicles that are shipped.
Stena Line are bringing some larger ships to the port next year because it's busier----do you think that they're worried about safety, Brexit or anything else ? Of course they're not. Neither must they turn a hair when they read about undesirables entering the country as they will continue to do so until they up their wages and stop using two people to do the job of six.
The quayside was blasted not long ago as being the worst for its lack of security but no mention of its lack of staff to do the job. No wonder these big companies profit, it's the slave labour they create. It's little wonder that the country is unsafe !
For two pins I'd write to the security division and tell them what I know, but my D depends on her job to pay her mortgage and I'd hate to open a can of worms and she lose her job. She's been there over 12 years in all weathers.