I used a trailer tug to move a 5,000 lb trailer up and down my driveway that is equally steep. Contact the companies direct and provide specs to them. With the steeper driveway I opted for a model with 3 wheels (each is very wide as with a golf cart) and gearing for the load. I went with a 100VAC model so all I needed was a long 12 gauge extension cord.
This is one such trailer tug though I bought mine from a company based in Calfornia and they provided the option of additional tires to provide more traction on the driveway.
https://airtug.com/product/trailer-tug-ld-electric/
https://parkit360.ca/collections/trailer-dollies/products/trailer-mover-10000lbs-capacity-base?variant=102111477776
Another possible option with a 4WD truck is to add a hitch receiver to the front of the frame and push the trailer up the driveway.