xdzt:Would "ĉiele serĉis nubojn" work?

It seems a slightly unusual way of putting it but I think it's basically fine. As mentioned it could be interpreted ambiguously, but when preceded by "The farmer leaned on the fence and..." it's hard to see how it could be misread. I would use "serĉis nubojn en la ĉielo" myself though.

Serĉi can be followed by por.

For example: serĉu por mi edzinon, or mi traserĉis la libron por vidi ĉu tiu eraro ripetiĝis.

But in any case what is going on in this passage is not exactly typical searching, more examining.

I am not absolutely convinced that serĉi X-on por Y-o is necessarily a mistake, where X is what you searched and Y is the thing sought.

Why not li serĉis ŝian vizaĝon por signo ke li trompiĝis?

EDIT:I have launched a thread in the Esperanto forums to see the general opinion as to whether plain 'serĉi' can sometimes take as an object the thing searched as opposed to the thing being searched for. From the initial reaction I am reminded that it is a different kettle of fish if you use 'priserĉi' or 'traserĉi' since these verbs can take as an object the thing searched.

Of course, I still prefer my own translation, 'La farmanto esploris la ĉielon por nuboj'.