I think the FAA would accept it if it incorporated at least the content of the current AC 61-65 tailwheel endorsement:
I certify that [First name, MI, Last name], [grade of pilot certificate], [certificate number], has received the required training of § 61.31(i) in a [make and model] of tailwheel airplane. I have determined that [he or she] is proficient in the operation of a tailwheel airplane
At this point There are two basic student solo logbook endorsements at this point. The completion of the required training endorsement which used to be on the student certificate, and the appropriate 90-day endorsement. It's certainly possible to combine those two and add the language of the tailwheel endorsement, and make them all one endorsement. Not difficult. Just requires a little creativity and an evaluation that the risk of being wrong or at least questioned (which affects both student and instructor) is less than the value of using less ink.