You just sell it on later with the WBS installed as a bonus. Just do a good job, with a good appliance, and then you’re all good.
You’ll have a relatively long time to advertise / sell it at the end of the build, so I’d make life comfortable for the build and stop panicking about minor issues.
Worst case, the roof can be put back ‘as was’ in a couple of hours with some plate, rivets, and CT1.
Even if it knocks a couple ok £k off the resale value, who cares?! It’ll save you 20x that in the long run anyways, so is basically sacrificial in terms of cost / loss.