I've not ever had to remove the front cover on an OM602/OM603 but here are the three reasons I'd pull the engine if I were in your shoes.

1) You have the equipment and experience to do it without breaking a sweat.

2) From what I can see in the OM603 engine manual the lower cover shares a piece of the gasket used to seal the lower oil pan, removal of the cover could mess up the gasket and I would not want to re-assemble the whole engine and then find out I've got an oil leak in a totally inaccessible place. With the engine out you could replace the entire lower pan gasket and get a 100% chance of a good seal.

3) You are never going to be able to clean the oil off the engine and get it as clean as the rest of your engine - with the engine in place. Your engine pictures are posted on the walls of my shop as the gold standard for clean engines, everybody that sees them is just in awe. I would NOT want to have to tell them "well yeah those pictures look really nice but the lower front half of the engine is now totally awash in oil"

Tim