By "shadowing a guide" do you mean you want to be mentored by one? That's a completely different story than attempting to stealthily follow a guide to his/her favorite haunts. If the former is the case, you might find a guide who is willing to show you the tricks of the trade if, in exchange, you were willing to do the "dirty work" at the beginning or end of the day. By that I mean cleaning/vacuming the boat, trading out batteries, changing sparkplugs, etc. If it's the latter, well, I wouldn't recommend it.