I just ordered two racing cans with separate vents…. see if those work
I, too, have all the same issues. I have a lot of old-style gas cans that I keep going when the spouts wear out.
I also have one of the VP racing gas cans I think you are referring to. There are two problems with them. First, they are so tall compared to their footprint that they tend to tip over easily. Not a problem if you have a bunch of them in a truck bed, but just one is tippy, and you have to secure it well.
The other problem is that it does have a vent, but the vent is so close the the spout that you can't tip it up much without gas coming our the vent. It needs to be at the other end, like you mentioned. To fix that, I put a fitting into the vent cap and attached a foot long hose to that. So now the vent is effectively a foot away from the outlet and higher.
For the modern gas cans, there are videos on YouTube showing you how to drill them and add a vent using a wheel rubber Shrader valve. That works, but the Shrader valve ID is very small, like about 1/8", so it doesn't flow much air, and thus the can doesn't flow much gas. What I do is just drill a 1/2" hole in the top of the can at the opposite end from the spout. Then when not pouring, I just plug the hole with either a .50 BMG bullet or a tapered stick. See pic of some of my cans.
I can't find the VP can vent thing I made right now, but hopefully you get the idea from the description.
As for the spouts, there are (or were) lots of places online where you can buy simple spouts that will fit the new threading on the new cans. The *(&^$% government even made the can companies change the spout thread to try to thwart the citizens from getting what they want.