Below is the most recent version of what I've been playing. My formal testing has consisted of three leagues and a local paper event, which has culminated in the middling record of 11-7-1. A few cards have varied across the lists, but the core has remained steady.
There's definitely room for improvement, but I am also certain that this is NOT the best thing to be doing with your Mishra's Workshops. Like you, I simply have an unhealthy fixation on prison shops these days.
Expedition Map Stax
mana rocks (8)
Generally, Expedition Maps for me have been expensive, colorless sinkholes, although I also use them for acceleration frequently to enable early plays. With all the basics around these days, getting a Strip Mine has often been game-breaking with or without Crucible. They are also an excellent enabler for Karn via getting Tolarian Academy.
Dunes of the Dead let's you keep a Smokestack at 2 with a Crucible out. Even without Crucible, it can allow you to keep a ramped Smokestack around a little longer. It also doubles as a finisher if you keep Smokestack at 1. Overall I've been pretty happy with it as a singleton.
Sadly, I've recently cut Tangle Wire, which has historically been one of my favorite cards. Without a reasonable clock on the board, they just don't do enough even with the synergy with Smokestack.