That's how I do it & I don't remember any strap attachment points on that lens so how else are you thinking of doing it?
Agreed but if Canon thought it was too heavy for the camera's strap they would either put lugs on the lens & recommend using them or recommend the tripod collar sling style. That said the choice is yours re what you like best or trust most.
I've never owned any of the Rebel bodies but I shoot radio control events & hang one or 2 bodies from their conventional straps for several hour a day, one body will have a 100-400 L IS, the other a 28-300 L IS or before that the old 35-350 L & before that a 70-200 f2.8 L IS. Bodies used have been 40D, 7D, 5D2, 1D2n, 1Ds2 & 1D4. To date no issues. Last fall I bought a 300 f2.8 L IS & it has strap lugs on the lens so I bought the strap & hang it that way.