1983 Plymouth Scamp GT

Fuse #16 blows as soon as key is in ON position.
This is the fuse for turn signals, hazards, tachometer, anti-diesel relay, and electronic spark advance module

I have checked for continuity in the connector, with the test between #10 and #9, and #10 and #8 giving a reading on the meter. These wires are #10 stop lamp, #8 left rear turn signal, #9 right rear turn signal. One reading is an order of magnitude larger than the other.

I have traced the wires from there to the turn signal switch with no shorts or loose connections. I have traced the wires from the wedge block to the bulkhead with no shorts or loose connections.

What's next? I need to drive out of state for work this week...

My manual says simply to test for continuity, but not what to do if there is a reading.
I'm assuming it's the turn signal switch, which look to run between $15-$30 online. Never taken apart a steering wheel before, and looks like a pretty invasive job, with special tools needed.

Is there any way to pinpoint what the problem is, particularly isolating a potentially faulty switch, without removing the steering wheel?
Some kind of rocker switch (like a moped) I can wire up somehow?