When you use analogies, like boarding trains and such, it becomes really important to clarify their meaning.
-- If being "on the Josh Heupel train" means being an unwavering Tennessee Vols fan and hoping that JH does an excellent job, I think you'd have at or near 100% of us on board.
-- If being on board means thinking Josh Heupel is the man to bring us back to championship football, I think you'd have more Vols fans who can't board yet, need to see some proof first. And you'd start to see 'no' answers.
-- If being on board means that we're married to CJH, I think you'd have far fewer answering yes. We're married to Tennessee football, not any single coach.* You'd get a significant percentage of 'no' responses here.
So it really depends on what you mean. I was optimistic and assumed you meant the first, so I picked "Yes." Looks like others have interpreted the question differently.
Go Vols!
* This doesn't mean Josh can't become a Vols legend that we revere for the rest of our lives. General Neyland did that. Josh can too. But that level of support for the man won't come until he brings the program glory.