I ran again today, for the first real playing session. I leaned a lot on random encounter tables and played dice to tell me if NPCs had any good or useful information.
The party started in a woods SW of Elblag, having been run out of that city by the 3rd MRD. They had a BMP and a HMMWV, with about 1/3 of full ethanol tanks. I had turned initial decision-making over to the player that wasn't 13, and was an Army vet. He played with Google maps, and planned a route SSE so as to avoid the Polish cavalry at Malbork before looping back to the Vistula. As there was a lake and a canal between them and the Soviets, they hoped they were staying on their side of it. He plotted a course that put them into patches of woods off country roads every 10km or so, to hole up for the night.
Dice served early to heighten the tension, their BMP had a suspension breakdown as they neared the end of their first leg. I allowed them to drag it off the road and into cover, but not very far from the road.
All the while, someone was watching them from the west. Every once in a while, their best spotter (Marine sniper gunny sergeant, of course) would see someone eying them with binos. (This was Polish cavalry, but only scouts with no interest in tangling with Americans headed away from them.)
A Polish refugee in the woods admitted that he had seen broken-down Soviet BMPs east of the canal, on the main route of the Soviets into Elblag (duh, this is the whole 9th Guards Army). With no suspension parts on hand, they sent 5 PCs in the Hummer to see if they could get lucky on the Soviet MSR. They got as far as the lake immediately south of Elblag, where they had a shouting-distance conversation with a Polish smuggler band (the smuggler had a wagon on a raft, towed by a motorboat). He was unhappy with them, and promised to bring some tracks tomorrow.
On to a village with a bridge, with a Soviet ammo depot on the east bank. Three PCs swam the canal in a midnight rainstorm, to see if they could raid the truckers and depot there. Instead, they triggered a firefight. All 3 PCs caught minor wounds while slaying lots and lots of entirely too gung-ho Soviets. The Hummer came blasting through town across the bridge with its MG roaring. Curiously, or not, the village militia didn't interfere with anyone or anything once the tracers started flying in large numbers.
When dawn came, the PCs were stripping the vehicles (a 2.5 ton with diesel in its tanks!) and bodies, the villagers came out to parley. They accepted some of the guns and ammo, offering light medical care and food and promising to redirect any Soviet comebacks elsewhere. They had no BMP tracks, but thought there was a Soviet vehicle repair depot 4km up the highway?
Meanwhile, the grumpy smuggler tried to ambush the PCs with a Soviet horse patrol. Instead, that patrol failed to notice the 2 Marine snipers hiding behind them and settled down at really short range. You can guess how that ended: all the Soviet patrol wiped out (1 Marine slightly wounded), the smugglers wiped out and their boat adrift.
Next game, the PCs are feeling gung-ho themselves, wanting to hunt down the rumored Soviet AFV repair depot after they rest up, brew some ethanol for a fuel reserve, and heal their minor wounds. I'll be reporting back in 3 weeks.
GM asides: I'd be strongly tempted to abandon the BMP, throw everything onto the deuce-and-a-half with diesel in its tanks, and keep moving south. Also, since they could have captured the motorboat, and they have to cross at least two rivers, including the wide Vistula, before getting back to friendly lines, I'd want to put that on one of the trucks or trailer for later use. I was really surprised when they handed the boat over to the refugee who helped them earlier.
Evil GM asides:

This is the early stages, when they get to collect stuff and think themselves powerful. Soon, I will show them some serious firepower and watch them scurry in terror! {rub hands, chuckle, rumble of thunder & lightning}
Rules thoughts: Oh, yeah, bullets don't hurt so much when everyone rolls 2d6 (AK74s & M16s) in v2. The .50 cal stuff really puts NPCs down, though.