No, though DeBows logically would have watched the results carefully and may have compiled their own numbers. They oversaw the contracting of the census takers etc. The contracting would have been done with the proper Federal authority, but just like the press and the mails, the process was carefully scrutinized. Southern society was not free. This was a necessity of having 3.5 million slaves. Every county had organized vigilance committees of free whites who were required to patrol the roads at night, usually well into the early morning. In the 1850's, the system was so effective that very few blacks made it out at all.
The patrol system easily turned itself into the KKK after the war. In essence, the effectiveness of the KKK was due to the fact that it had essentially long before been organized and instituted, though under the name of the Vigilance committees. The Vigilance committees played a vital role for King Cotton in controlling the voting in elections before the war, just as the KKK proved so adept at the same game after the war.
Both the mail and the press were censored, if not by pre-print review, certainly by response to any materials considered to put a negative view on slavery. It was not at all uncommon to have newspapers closed down for expressing the wrong thouhts, and the mail system was such that everyone had their business poked into with a fair amount of nosiness. It was all viewed in the common interest, but it was intolerance of the first class.
There were a number of grave errors in the 1787 constitution, and certainly the 3/5ths rule was a major one. Large slave owners had a profoundly stronger political influence on all levels of the government, from the Feds on down. This was particularly magnified by the fact that the southern Congressman were the conduits for the Federal pork which was such a major part of the southern economy. Federal expenses for the Freedman's Bureau, which spent more money on poor southern whites than on southern blacks were actually less than the total graft and financial support the southern states received through almost every federal agency and program. Given there weren't many at the time, it was quite remarkable. Southern Custom houses handled a mere fraction of the tariff responsibilities, yet they all cost many many times the price of the New York custom house that handled the by far the largest part of it. Military infrastructure expenses predominated in the south. Millions were spent on antiquated forts like Ft Sumter. Most Northern cities had not such forts, but Charleston had three. All built by slave labor charged off at 3 bucks a head an hour while the slaves were compensated at about 7 dollars a year. Land schemes, the post office, fugitive slave marshalls, state militia's, mints etc. The list goes on and on. On top of that was the private debts and the long list of Northern companies gone bankrupt from cancelled southern debts. Small wonder that secession in the North didn't cause all that much stir at first. A lot of Northerners were probably happy to see the nonsense go, but eventually the realiziation of the fact that if the North didn't support them, someone else in Europe would starting setting off the alarms.