Rogue Leader said:

So in my opinion the T-47 could be the snowspeeder and "smaller modules into the transports" mean something like snowspeeder bikes? I don't see why not... Maybe they couldn't get them to work but they could pack'em up and use'em else where, thus "getting the smaller modules in to the transports". Mmmm... "but we don't SEE speeder bikes..." some would say... no we don't... but we know they exist (at least on the Imperial side lol). In a galaxy full of fun and fancy repulsor tech why use a smelly bipedal animals (other than the cool/interesting factor)? Mmm... ah well. In my mind it make sense... then again I am slightly crazy... =D So whatever.

In a roundabout way, you answered your own question. Maybe they resorted to riding Tauntauns BECAUSE they couldn't get the speeder bikes to work in the cold.