That's a different (larger) model than the furnace used in any Escape... and this forum is specifically dedicated to small moulded fiberglass travel trailers from Escape Trailer Industries. The details of sail switch location vary between furnace models.
While taking a quick look around the net for information about a 40k btu furnace sail switch, I found that there is not a lot of websites that offer the type of support that the Escape Forum does. I imagine we are somewhat blessed that we have the abundance of technical help that we do for our trailers.
That said, I did find several 40k btu furnaces that could be the one the OP is asking about.