You actually can get up on the hospital downtown prior to G-spotlight if you really want to and complete 2 of 3 unique jumps that you get on G-spotlight....the one you will be missing is the one out the window when you start it.
This embankment is just south of the hospital. You aproach from the west but you have to start in the open yard to the north a bit and turn to the east to get up speed. Its kind of hard to get up there (I've done it about 6-8 times)...if you morph to a bike, its alot easier.
If I remember correctly you turn to the right a bit as you hit the embankment.
You sort of boomerang off that wall on your right and get shot off to the left-- when not morphed you will wipe out alot. Even if you don't want to the jumps early, its a fun jump to do--when you are playing for fun.
As far as my "quick" 100% quest, I'm at 42% done. I've done all storyline up to Copland, Completed Pole postion, Boatyard, Kaufmann cabs, Malibu, lovefist, Mitch baker, all 5 assasination missions.
Stuff I'm working on: 45 hidden packages, 1 rampage, 1 unique jump, I've done 2 of 6 street races, Stolen car lists for SSA--I'm not really working on these, when I see a car on a list, I grab it and either store it or drive it to SSA.
Still have to buy and do film studio and printworks, cuban and haitian missions, Phils missions, Pizzaboy, taxi, stadium events, RC races, Trial by dirt, test track, shooting range, and all 4 chopper checkpoints.
I'm at 7.5 hours so far.
Spuds.
*****EDIT***
Played another hour today. Got all the hidden packages, robbed 7/15 stores, 1 rampage, started doing film studio missions. 8.5 hours 48% done.