Try using a gravel stabiliser! I used one on my driveway (which was also on a slope.. pain in the a***!)
The one I used was called COREgravel coredrive, and it has really helped
I saw this other forum which was saying how these grids must have a weed membrane already attached- so when i was hunting for a grid coregravel popped up a lot.. and i must say the weed membrane is helping a lot
While we were doing the drive we also did a couple paths leading to the house, which this grid could also help with!! Bonus
plus it only cost me £11m2 (Id check the current prices, this was a year or so ago)
