Hello Diana. If I were you I would go the highway and through Mt Boyce bridge, dual road up to Katoomba, no stress of a convoy of impatient car drivers behind taking risks to pass. The chaps at Boyce will soon put you straight when you get there if they pull you into the shed, just explain the situation and I'm sure they will help, as long as you leave any attitude at home. You may even get the arrow back onto the highway without going through the shed. As far as making you unload if you are heavy is concerned that is not going to happen. They will only ground the vehicle if it is a certain percentage over which I don't think would be possible given the room on the back of the inter, unless you plan on carrying a heap of armour plate over there, or something similar. What a single axle is rated at in all the brochures does not really matter, it is the manufacturers rating that is recognised and if there is no plate they will probably go by the army rating of 2.5 tonne. If you want to up that it is a matter of an engineers report to say that the truck is capable of carrying more and that is very involved, affecting brakes, air capacity, air build up time, etc etc etc. As far as going past without going in to the bridge, don't even think about it, it is just plain stupid, the fines are not worth it, and the log book is only required if you are travelling over 100ks as the crow flies from the registered address of the truck. I hope this bit of info helps. Regards, Bruce.