#1
I am working on a strat and the neck joint is real big and in the way when playing the higher frets, so I am going to shave it down a bit, and maybe cut a part off so it would only have 3 screws holding it instead of 4.

Do you think the tension from the strings would be too much for only 3 screws?
#2
Some fenders in the 70's - and a lot of cheap guitars since then- have been made with 3 neck bolts. However, those were in a triangle shape with the tip of the triangle in the middle of the neck pocket. I'm not sure you'd have good results just pulling one of the bolts on a 4 bolt model.
Do some research on the Fender Contour heel. It's four bolts, but the one closest to your fretting fingers is moved towards the body so that the heel can be cut away in the way you describe.
It was on the Jeff beck strat and I think the deluxe and 50th anniversary strats.
Maybe you could find a neck plate for one of those and just drill a hole for the offset bolt.
#4
^Problem is, I don't think anybody knows how much tension it would take to significantly affect the joint, or even what the acceptable range for neck play is. Maybe fender does, but they're not telling. And they certainly won't have data for a 4 bolt joint with 3 bolts in.

Of course, you could find out the hard way. For science. Then get a new neck.
#5
How about an Ibanez style All Access Neck Joint (AANJ).

They are easy to play on and they seem to work fine for a lot of guitar companies.
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