I was hoping to get something that I could buy locally. The rim I have for my spare doesn’t have a valve stem and I’d like to take a spare with me this weekend.
It's generally considered a bad idea to modify wheels in any way unless you are a professional engineer. I doubt just drilling the hole out round would cause an issue, but way too much liability if a wheel fails for me to say it's a good idea.
Just a thought, but take the spare with you anyway, and if one of your tires does fail, have the tools with you to remove the front portion of the wheel off the rim, and just swap that front plate over to your spare tire if necessary, plus an air compressor to inflate it.
The tools and air compressor are a good idea to have on hand anyway if you're planning on taking your truck off road. All you really need are the air compressor, a socket, ratchet, and torque wrench, and take a copy of the torque sequence with you. A pry bar and a hammer to get the wheel half off the tire rim is also a good idea, as they tend to stick.
If your spare is a different bolt pattern, do the same thing but you can steal the valve assembly instead of just swapping the wheel plate.
another option is AAA+ towing, so that you can get your truck home (well, depending on how far you are going; I have the 100 miles towing and there is a 200 mile option)