Nowadays the only way is the helicopter. However, in older patches the van actually stayed until about a minute into the heist, then it'd be a helicopter escape. ^-^
Wow I remember trying this a while ago and I was just standing touching the front right tire of the van and after about 6 seconds of just standing there and not getting the end screen I thought it wasn't possible since the box just disappeared and then van would drive away. I would just do what you did, open all atms, grab all jewelry, if there was a money back in a safe I would keep it on my back when going into heli or if not a jewelry bag.
You can go back and play it! Theres a way to download old version of payday by using a depot downloader, the only issue is that save data was changed ~ update 100 or so, so you may need to backup your save before doing so!
The overly priced windows aren't the ones at the entrance, it's the roof ones in the back area of the mall - the reason the money spikes so quickly is because of one of my grenades landing up by the car on the left - which is worth 20k if i remember rightly
