Alright, a couple of things:
-Can we not put alphanumerical codes in front of everything? GOFAST doesn't have it, DUC doesn't have it, and frankly Instant Roads shouldn't have had it. Only equipment should have it. Electrogel should just be Electrogel.
-I reckon Electrogel would be Easy, and once we have it, Bear Armour would be Easy too. Now, there's something to be said for doing Easy things to guarantee some level of success, but we must also consider action economy. I'd rather go straight for Bear Armour at Hard. If we must do them separately, can we at least do Electrogel as a revision?
-CW has given us some pretty big hints as to how we might improve the Burrower. If we put them together, we get something like
HUT-57 Excavator: Following on from our success with the Burrower, the Excavator is a more confident, impressive vehicle. With a strengthened drill, reinforced hull, and more powerful engine, it is capable of going deeper than the Burrower ever could, without losing much in the way of speed. A (relatively simple) navigation-computer uses heading and velocity information to calculate and display the craft's (approximate) position, allowing for longer stints underground without getting (very) lost.
The Excavator has a turret armed with dual Velociraptors, though it is left fairly modular such that other weapons could easily be installed. Underground, the turret is protected by a cowl. Above ground, the cowl folds away, and the turret extends upwards, giving the gunner a clear line of sight all around the vehicle.
Despite increased armour, we expect the Excavator to be capable of moving at a reasonable pace, thanks to its more powerful engines. And with its ability to go deeper than the Burrower, it should be possible to outflank enemy positions. We imagine the Excavator harassing enemy supply lines, hitting vulnerable command centers, or joining the main force as a flanking force- and then retreating underground before reprisal can be mustered.