[Neil Lowe]

Will it be easy to swap them later?
Won't be able to just swap all of the concrete plates because some will be used for airfields.

Not if you've used them elsewhere in the map you wouldn't want changed. Otherwise you'd just edit the actors.static in a hex editor to call on the similarly named new object/s when your ready. Did that with some trees I was messing with, was able to swap different ones in and out with relative ease.

Cheers, Neil