I'd steer clear of Skullduggery until you have some mentalism miles under your belt. It is mostly impromptu, but it also deals mostly with effects based on suggestion and audience management. Not easy material for a beginner.
The best impromptu mental effect is cold reading. Learn everything you can about it. It will allow you to turn a simple center tear into a 10 minute miracle.
I can tell from your writing and word choice that you are a smart guy. You probably are into coin magic. I bet you've combed through Bobo's book letter by letter. Studied David Roth's every move. My guess is you have a pretty good spellbound routine you'd like to do more often, and you love your craft enough to put in the work to learn more challenging moves like the muscle pass. Guys like you always have many demands on their time, but make an extra effort to explore some cold-reading resources. You won't be disappointed, and you'll have even better rapport with your magic spectators as a bonus.
(That last paragraph was a little bit of cold reading.)
