No need for a bonus. I'm not even sure you can provide one after you have already rated, but that's totally ok. I did not say that it was a necessity. None of what I recommended is a necessity other than proving you have been accepted into a school, have the funds to pay the tuition and living expenses, have an unrelinquished domicile at home, and will be returning when you are done. The reason I recommend entering at different times is because one entering on a B visa is not as suspicious as a family entering together. If they think that your spouse has stayed behind, they would think that you would go back to your spouse and have less reason to stay in the U.S. You could just as well travel on the same plane and get in different lines at the Port of Entry. That might work as well. It was just a suggestion. But if the officer asks if you are traveling with someone, you cannot lie.
As far as changing status from B to F inside of the U.S., you do not need an excuse to do so. It is perfectly legal to do so once you are already in the U.S.
If you are denied the F-1 outside of the U.S., it is possible that you could have a problem using the B to enter. They will may be able to see it in their system that you were denied and if the reason is that you were deemed to have immigrant intent and that's why you were denied, that would be a reason that they would deny you entry on the B visa. So this is why I say it is safer to change status inside of the U.S.
And finally, you hit on the downside of changing status in the U.S. While it is safer, you do not and cannot get a visa stamp inside of the U.S. You have to leave the U.S. and apply to get a visa stamp at a U.S. Embassy or Consulate
. It may be possible to go to Canada to do that so that you do not have to go all the way home.
Thank you for the good rating. If you would like to request me in the future, please remember to put my name in the subject box. Good luck to you!