Tripod / head weight ratings are all calculated with the weight directly above the pivot point of the head.
As soon as you add an off balance load either from a lens, macro rail or both you are effectively applying a lever to the tripod/head assembly. If you try to compensate by over tightening the head it will result in damage and decreased holding ability.
If you do use a focusing rail, (generally a good idea for macro) try to end up with the apex of the tripod under the camera. Many macro shooters who use rails, also take advantage of secondary support---- small articulating arms that go between a tripod leg and the front of the rail - this adds lots of support for not a lot of money.
If you are handy you can make such things yourself.

I have a Nikon Nikkor 105mm 2.8G Macro lens I use more than any other lens. I have a light cube I shoot into for small objects. I have a Giottos MH 1000 ball head with a Nikon D810 & a D3 but every time I go to compose the shot it drifts out of composition just enough that it ruins the shot and fixed heads are worse, and I'm talking about a 30-degree angle. I have to guestamate where it is going to settle in the composition multiple times before I get the shot where I want it. I know the more expensive the ball head the less drift I get but I can't afford a $500.00 head. and I quit trying with the D3 because it is a tank. Any suggestions for it to stop drifting?

These are not pretty and quite rudimentary in design, but they work and do not drift.

You may be able to find these older models of Manfrotto heads on the used market at reasonable prices. I don't know for sure if the current models are as sturdy. It may be wise to check them out as well.
Thank you, Mr. Shapiro, your knowledge a plus in this craft.

In the attached image there are 2 older models- the heavy-duty ball head and the one-handed trigger ball head. Both have these controls. The larger one could accommodate a 4x5 press or view camera.

As you can see in the picture, the rater's large locking lever provides ample leverage and looks the ball in place even with large lenses. A 105 macro would not be a difficult load.

I have never had a camera drift or lunge forward at any angle.

In macro work, drift will cause difficulties with your composition and will play havoc with focus too!

Of course, yo tripod would need to be sturdy enough to hand the additional load. If the tripod is not sturdy and stable, even the best head will be ineffective.

The more expensive brands such as Arca Swiss are excellent, have superior finishing and are well suited for more precose panoramic work- the are strong as well but they are more costly.

These are not pretty and quite rudimentary in design, but they work and do not drift.

You may be able to find these older models of Manfrotto heads on the used market at reasonable prices. I don't know for sure if the current models are as sturdy. It may be wise to check them out as well.
I don't know if the reply was sent, but your opinion means a lot in this craft.

In the attached image there are 2 older models- the heavy-duty ball head and the one-handed trigger ball head. Both have these controls. The larger one could accommodate a 4x5 press or view camera.

As you can see in the picture, the rater's large locking lever provides ample leverage and looks the ball in place even with large lenses. A 105 macro would not be a difficult load.

I have never had a camera drift or lunge forward at any angle.

In macro work, drift will cause difficulties with your composition and will play havoc with focus too!

Of course, yo tripod would need to be sturdy enough to hand the additional load. If the tripod is not sturdy and stable, even the best head will be ineffective.

The more expensive brands such as Arca Swiss are excellent, have superior finishing and are well suited for more precose panoramic work- the are strong as well but they are more costly.