Well, I managed to get into the west side of the city in Vice City by abusing a series of ramps near the movie studio and bridge, and got the rest of the hidden packages, but getting the very last one was a royal pain in the ass.
I needed a boat for the last two packages, and I got one by landing a helicopter (easily obtained in the west city) on the locked-off docks. I picked up the second-last package, but triggered a Rampage mission while walking up to it. It was a fairly easy one, picking off boats with a rocket launcher, but I aimed a little too far to the right once and hit the fence next to me, killing me. In order to get that very last package, barely a stone’s throw from where I already was, I had to go back to the ramps, break into the west city, steal a helicopter, fly it all the way across the map back to the east side, land on the docks, and get a boat again. Argh.
One of the things unlocked by those packages was the tank, but I still had to go get it from the army base. I bought a condo on the north side of the west city to store it in, headed to the army base and charged in, got the tank, and then hit a light pole on the way out. That let the army guys grab me out of the tank, and although they didn’t bust me, I couldn’t get back in the tank without them instantly pulling me out again. They were also shooting at me and it wasn’t long before they’d worn down my health, so I figured I’d just reload and try again.
Except that my last save game put me back in the east city, with that one last package still to go. ARGH. I thought I’d saved after buying the condo, but apparently not, so I get to do it all over again.