My son, who is a quadriplegic with a power/tilt-back wheelchair(450 lbs) - has an aluminum folding ramp that he uses to get his chair
in-and out-of, the van his girlfriend/care-giver drives.
He also uses it to get his wheelchair into my house that has 5 steps
up, to get into the front door.
The ramp is very compact and folds into 1/4's and is easy to transport.
Check with wheelchair or handicap accessory sellers, or possibly eBay.