Watch the Travis Train Whistle online guitar lesson by TrueFire from Play Acoustic Guitar 6: Lick Lexicon
Travis Train Whistle - E Lick 11 is a video guitar lesson presented by David Hamburger and is sourced from Fingerstyle Blues Factory.
As in Merle Travis, singer, songwriter (though not an, ahem, singer-songwriter, if you see what I mean) and fingerpicker extraordinaire, composer of both "Sixteen Tons" and "Cannonball Rag," if you can wrap your head around that for a moment. Also an inspiration to Chet Atkins and the person you're invoking any time you mention "Travis picking." In this case, far from playing a basic "Travis picking pattern," we're laying in a whole assortment of funky minor pentatonic licks over an alternating bass. Behold! It can be done. Feel free to goose those flat thirds on the high string with a quarter tone bend up towards the major third.