Harry would have used old fashioned paper maps to lay out the grid of LC, but wouldn’t have a visual record unless he took photographs on an old fashioned film camera (he’s used disposables in the past). The internet records would allow him to access elevation plan detail as well as photos much faster.
Demonreach would be massively easier still because of his Intellectus, he can easily add contours, structures, trees because he knows them perfectly, and it is less prone to change than LC. A smaller project that can be accomplished in a much shorter time with less of an impact on the narrative but adding massively to his overall security in eliminating many of his trips to the island. Harry might be able to summon Alfred in person to LD and whatever he is carrying, and would increase his control over Alfred (just when he is having doubts)