Yeah, 10' too long might be tough to pull off. I can see getting away with 4-5 extra feet, but 10 would be very visible.
Where is your buddy coming from? I
think 65' is the limit here in Colorado as well. I come in right at 63'. Hmmm, now that I say that, I had better remeasure mine now since I bought the new truck with the long box....🤷♂️