My father has just taken delivery of a Hamer lift (As shown above). It uses farm jacks at each corner, which you have to operate in turn, a bit at a time. It's slower than a professional ramp but it requires no power, apart from that of the operator. It's got a few heavyish components but it seems well made and it works.
You can get a seat (They use second hand reclining car seats) on braked castor wheels, so although you can't stand up, you can work at a comfortable level relative to the car.
They are quite a lot of money but I dare say a lot cheaper than a professional ramp and less bulky; the Hamer one is quite unobrusive when in place and can be taken apart with just eight bolts.
I don't know anything about regulations banning pits. When I hear tales of H&S inspectors insisting on fire exit signs in a wigwam, I'll believe anything

.