In the end, it was quicker to go through the list of unique jumps I thought
I'd done, and try each a few times to see if I could get it to trigger.
There are 36 jumps in VC, I thought I'd done 33, the missing one was only
discovered after I retried 30 of them, several times each.
I've not bothered doing the last three jumps because one of them is
impossible to get to until the mission where advertise the film on the side
of the building. The other two are possible, but not worth the effort as
they are also done during the mission.
So now I have a savegame with all the boring stuff that's unlocked at the
start and needed for 100% completion already done - just the story, side and
asset missions to be done, as well as the boring stuff that's locked at the
start (chopper checkpoints, rifle range and payphone assassinations) and
those three jumps.
Tommy hasn't even looked in on his well-stocked Ocean View hotel room yet,
but the save game includes all the hidden packages, all the non-asset save
points, the three stadium events, the RC challenges, the four driving
challenges (Cone Crazy , PCJ Playground , Trial By Dirt , Test Track), store
robberies, and the taxi, vigilante, firefighter, ambulance and pizza
missions.