>You should not work in the field while the sun was being hot.  

Came across this sentence and it felt a little flawed, Original sentence is not from a native speaker. I think it should be either:

>you should not have worked in the field while the sun was being hot.

or:

>you should not work in the field while the sun is being hot.

Maybe dropping the "while" would be a better idea, but my question is- can a sentence have two different tense like this.