You will only change torque by adding extensions on air or electric tools. A common torque wrench with extension will not be effected. If the head of the wrench is not straight on as in tweaked a little that will effect it also. Just make sure heads on good and flat, and torque all day with...
Not trying to be a **** but there are a ton more reasons then that. It's not that odd to have to pull the cab. Although the 6.7's are "supposed" to be designed so you don't have to as often.
Flex heads, swivel sockets (every socket set you have get a swivel set) short, medium, long, longer and long as all get out extensions, swivels. Just the normal stuff. Lol