There would be a number of ways to implement a interstate travel restriction without physical check points. The most obvious is put people on the no fly list who can’t or won’t provide proof of vax. Flying is a FAA sanctioned privilege wholly controlled by fedgov. Fedgov also controls Amtrak and every international border crossing ditto for ships entering or leaving US waters. Fedgov can put annoying TSA check points up at every train station if they chose too no vax no pass simple for them when they can just print money for more TSA goons.
You hit the nail with out of state ID, but missed the obvious with modern technology who-fencing works not only for smartphones but also for credit cards and with licence plate scanners in a lot of police cars now another source of geodata. The first time someone tries to use their credit card out of state and doesn’t provide proof of vax the CC company can turn off that card until it is back in its home state. Same for licence plate scanners out of state plates would be probable cause for a traffic stop no proof of vax that plate gets flagged and now every time another plate scanners on the network scans it the officer is alerted of the state LEOs go along with the travel bans then they are the enforcement arm along with big biz. Technology such as face scanners makes for some real 1984 type scenarios pretty quickly. One flag as unvaccinated into the face scanners network and it get to minority report type tracking. The average person is on camera 20+ times per day any one of those could be plugged into a face recognition device and networked.
The question is not if the fedgov with the help of states could put a travel ban its should they what is to be gained given that the same fedgov is sending infected illegals all over anyways. The feds already don’t care about the constitution stop thinking they do that’s a complete fallacy at this point arguing over the constitutionality of something when the gov itself don’t care anymore is futile. The power rest with the state’s in this case other than Air and trains the.logistics are simply to great to block road travel without help from the state’s. Texas is not a bad place to be trapped in other than gambling, fly fishing,skiing and tropical beaches not covered in seaweed,oil and illegals there’s little reason to leave Texas anyway.
I believe you mean that a vaccination record would be tied to a plate number, correct?