Oscar, don't understand why you would want to create a bad situation but to each their own. As a veteran of 700 + crossings/encounters with border personnel at both SY and Otay they can be a pain if they want to be. I got tired of some of their idiotic questions back in 98 and did some serious research on it.
( Fact ) Officers at the line can ask any question(s) they want, that does not mean you have to answer them. Not to do so will probably bring secondary inspection and a waste of your time. The mandatory requirements for re-entry to the U S for a citizen
( by land ) are; 1- Declare yourself to be an American citizen 2- Produce proper documentation ( Calif driver lic is sufficient for now ) 3- Declare what you are bringing back that was purchased in Mexico. 4- Make yourself and your vehicle ( if pplicable ) available for search. IT'S THAT SIMPLE... Anything else is BS. That is from the head of Customs back in 98 or 99 in a personal written response to me.
I have always crossed over by car ; my " going to Mexico car " which is an older vehicle. The " at-large " ( before reaching the guard shack but after the USA boundary line ) officers use to piss me off. They would come up and ask me if I was the registered owner of the vehicle then ask to see the registration. What the hell, I'm in America ( Calif ) and can drive any car with the owners permission. Add to this the fact that 9 out 10 Mex registered cars crossing probably are not insured and this really ticked me off since they received no scrutiny.
After 5-6 of these encounters I was fed up and took it out on the guy. He popped and made a statement that ever since has been my trump card. ( Quote ) We ask for registration if we see a middle-aged male, driving alone , in an older car because it may be stolen. My acid remark to him was; people do not steal cars in Mexico and take them to the United States, it's the otherway around ! He could not recover from this. ( Obviously, it has to do with drug smuggling )
My 2 hour drive home gave me time to think this over. The United States Gvt is
" profiling " which is something the officer of the day venomously denied on two subsequent occasions. Those two occasions I was asked for registration by the " at large officer ". I politely told him I would be happy to show him the registration right after we ( he and I ) have a talk with the Officer of the Day in secondary about PROFILING ( nobody ever asks to go to secondary ) Needless to say the registration became a moot point right away.
Bottom line; if your a U S citizen with proper ID, make a full and complete declaration , open yourself to inspection you do not have to answer any questions ( they do have the right to search even with declaration ).
Hope this answers your question.