Dinamically keep track of server center

For a lot of datapacks, there is a need for the existence of a sign (for json text interpretation) and of a shulker box (for inventory manipulations) somewhere in the world. One would use them encased in a bedrock at 0 0 0 but if the server is not centered around this point (world spawn has been moved for example), you need to have the 0 0 chunk forceloaded. 
One idea I have is instead of putting this formation at 0 0 0, is to use the context of the reload function to summon a marker and the block formation at server position and access the needed block through execute at/positioned as @e[type=marker,tag=server.center,limit=1] run whatever you want to do with these block. Would the entity search make a great difference from using explicit coordinates with a constantly loaded chunk ?
And also, is there a big difference between execute at entity and execute postioned as entity ?