Is this an appropriate thing to send after a first date?

Alright, slow down and relax. You're just like me in situations like these: I catastrophize the issue in my head and then feel like I demand an honest answer why things didn't work out. First off, you have every right to be treated with respect and honesty so don't write that it was a mistake thinking that! Second, you're going a bit extreme here for a first date. I know it's frustration going from person to person and not have things work out over and over but technically you guys both don't know each other very well and a text like that is too serious.

Here's what to do, just text him saying how are you? What you up to today? Be curious about him and just fire up a conversation and then you can drop in an apology for sounding so dismissive on the first date. if I was in his shoes and you told me what you said at the end of the date, I'd be demanding an explanation with a lengthy text haha. So there ya go, what to do. Hope it works out for you :)

"He answered with "Yeah I had fun too!" so I didn't respond because I took it as a blow off."

I think his exclamation mark indicates enthusiasm, so I don't think he was blowing you off. He'd probably give you a one word answer if he was blowing you off like "yeah" or "thanks".

You: "I had a great time!"
Him: "yeah"

Or...

You: "Have a safe drive home!"
Him: "thanx"

Moving on...

Do yourself a favor and DON'T post that message that you are planning on posting.

Do you want a relationship with this guy or not? From what you've posted, he seems like he's probably interested, but you're basically breaking up with him before a relationship has even begun. Don't do that!

"It's been a few days and not having any communication on your part..."

I didn't see anything in the first section where he wasn't communicating with you. The last thing you have him doing in the first section is messaging you with "Yeah I had fun too!" - to which YOU didn't respond (you say "so I didn't respond because I took it as a blow off"). So you don't respond to him, but then you're about go off on him for not communicating with you?

(Even though it's a bad idea to send him your message, don't feel bad about wanting to do so. I'm the king of doing things that seemed right at the time, but then look back and think "what the f*ck was I thinking?!?!")

wtf? Don't say that! You confused him by saying OK thank you and kind of rushing to get out of the car. You can still save this provided you haven't sent him any of these texts. This guy liked you enough to drive an hour to see you. Honestly you need to apologize to him. Just be like sorry I think I may have ran you off the other day at the end of the date. I was actually hoping for a kiss but I got kind of nervous and panicked at the end. Hopefully I didn't scare you off cause you're really cute. Text him that. Ok?

Umm what the Hell kind of text is this?

Unless you want to make an enemy out of him, don't send something so silly to him. Seriously that is taking it to the Extreme, when simply asking him sup without already assuming bad things.

Things come up in life, unless you learn to accept this, Many future relationship may not go according to your plan.

In my head I would be thinking "Dafuq is this?" and I would just send back something like "I assumed that you wouldn't want to go out again after the non awesome end to our date. Sorry for any confusion, and good luck on your journey as well"

It's a pretty ridiculous thing to send.

do not send that! he just said he had fun - that is a good thing! you should text him normally and ask how he is?

Ah that's pretty harsh to send him that especially because it seems like he was into you and all of that has only happened because of a lack of communication.
I think you should ask him out instead of sending him a letter full of grief. he was the one telling you should do it again and you're the one who didn't say it back in the first place. In my opinion, he's scared you're gonna turn him down if he asks to see you again. And the letter will confuse him even more, and make you look like the girl who doesn't know what she wants and then blame him for not understanding your mixed signals. In a word, it won't make you look good at all.
Ask him out and at least you'll know for sure whether he is into you or not :)