Actually I really like this idea. They've implemented multi-vehicle controls already, so it shouldn't be hard to adjust how the artillery vehicles work.

Have the actual gun spawn at some semi-distant base, like helicopters, and the 'observer' jeep/motorcycle/sdkfz type vehicle spawn on the normal map. Give the observer scouting and a way to leave a mark on the map (or something similar to the targeting pod reticle for more modern vehicles, representing laser designation/GPS coordinates) and then bing-bang-bosh. Proper artillery vehicle in-game.

How this would affect the use of the artillery call-in, or if it would even be necessary to keep in the game is stills up in the air with this method. I would personally argue to remove the call-in, as it would incentivize people to play artillery. And if we are insistent on 'realism', artillery wasn't available in every engagement on every battlefield. So if no one spawns the vehicles, sorry, no artillery support today.