It is called a gun raid, it is a military tactic that already exists as quite a fleshed out battle concept that relies primarily on a similar shortsightedness to yours in what defenders expect, by the time it is realized a vulnerable asset is near the frontline the artillery system has fulfilled its fire mission and there are now much bigger issues for the defenders to focus on.

Another commonly employed tactical method for offensive operations is the artillery raid. The artillery raid is a rapid air or rapid ground movement of elements into a position to attack a high- payoff target currently beyond the maximum range of available field artillery weapons. This could involve operations across the forward edge of the battle area. Normally, a raid is extremely short and does not involve sustained operations. A detailed plan, surprise, and speedy execution are key factors in a successful raid. Firing units will move forward only the number of vehicles necessary to accomplish the mission. When the fire mission is complete, the howitzer crews prepare the howitzers for movement.

https://companyleader.themilitaryleader.com/2020/03/09/offensive-operations-for-the-field-artillery-battalion-and-below/

https://www.centcom.mil/MEDIA/NEWS-ARTICLES/News-Article-View/Article/948203/the-gun-raid/

https://www.armyrecognition.com/news/army-news/2025/u-s-army-artillery-trains-for-high-end-war-with-helicopter-supplied-gun-raids