CalifJim at English Forums has valuable advice on the issue of 'may prepositional phrases be used as subjects [/objects] in sentences?'
for you to meet the king [would be impossible]
[uses] a for ... to ... clause. for is considered a complementizer in
that context (according to some analytical methods), not a
But you can make a prepositional phrase a 'sort of' subject by pulling
it to the beginning. The resulting sentences are 'pretty lame',
however, and not all grammarians will likely agree that these phrases
are true subjects, since the sentences can be analyzed as something
like cleft transformations of an underlying sentence with a different
In the office is where you'll find him. [You'll find him in the
Before the war was when they met. [They met before the war.]
With great care was how they proceeded. [They proceeded with great
So 'Over land didn't seem much easier.' shouldn't cause many knee-jerk reactions in conversational style, but in formal writing one might like to add 'Going / Journeying'. In this example, even the 'straightened' form might be considered to benefit from the addition of the ing-form: It didn't seem much easier going over land.