There's no need for a professional writer.
This may be the ticket:
I was looking at the map and contemplating the drive, the cost of gas, my sanity, and I have come to the conclusion that...
NOT A TEACHER
(1) You are correct in the sense that you, as a writer, may write
anything you wish. In fact, I think that some of the greatest
writers in English have broken the rules. But, as I understand it,
one may break the rules only after s/he knows that a rule is
being broken.
(2) I cannot put my finger on it, but your sentence seems
to lead your reader astray (just a little tiny bit).
(3) Let me try to explain:
(a) Look at this sentence: I am contemplating the drive, the
cost of gas, the sanity, and I have come to the conclusion that ....
(i) The sentence seems -- at first reading -- to say that you
are contemplating 4 things: the drive, the cost of gas, the
sanity, and I have come to the conclusion.
(ii) As you know, the first three are nouns, and the fourth is a sentence.
For example, would you agree that the following is infelicitous (not
a "happy" use of words):
I like ice cream, pie, candy, and I am now baking some donuts. (It
seems to say that I like four things.)
Woudn't it be clearer to write:
I like ice cream, pie,
and candy. I am now baking some donuts.
OR
I like ice cream, pie,
and candy,
and I am now baking some donuts.
(4) As I said, a writer may write anything s/he wishes. But I have
read that if a writer loses his/her reader (that is, if a reader has to
stop and think what the writer is trying to say), then the writer
has "failed."
(4) You do not wish to use "and" in front of "my sanity." You say that
it gives a "deadpan" sense. Well, then, you should do what you wish.
I am sure that every reader would understand what you wish to express.
Best of luck to you on your writing career.
James