That load has no significant inductance, so you don't need the diode.
You do know what inductors are?

 

That load has no significant inductance, so you don't need the diode.
You do know what inductors are?

I didn't before but I do now.
Seriously, thank you for being so helpful. It's very much appreciated.

 

For R2, the closest I can find locally is 68K or 75K. Will either of these suffice?

 

For R2, the closest I can find locally is 68K or 75K. Will either of these suffice?

Either should work.
It controls the PWM frequency, which is not critical.

 

Built a couple of these circuits with the same result. 12.4v supply. Trigger open = 2.9v out; trigger closed = 5.7v out.

 

Built a couple of these circuits with the same result. 12.4v supply. Trigger open = 2.9v out; trigger closed = 5.7v out.

What circuit?
Where are you measuring "out"?