Man arnt going to fit something in there lorries that is going to have you crashing into this that & every thing are they , do you doubt your a-z , lorry drivers map , google , do you doubt yourself , it’s not a dig at you , but it does make I laugh that no-one trusts a lorry specific sat nav , but a map , google that could just as easy be wrong they trust 100% .
Personally I’d stick in the specific dimensions for the lorry & see where it takes me