How do I ... earn his respect ...?
Short and sweet: Don't.
As long as he isn't outright rude, derogatory, mean, hostile, you name it - treat him with respect to follow your ethics, and let him follow his.
Do not lecture, preach, teach manners. Chances are that he is behaving like this towards everybody, and it has nothing to do with you, but with him.
Here's a quote (source unknown to me) that I think could apply here:
"I'd rather be rich than right"
I learned that I was able to be more successful and make more money than many of my competitors because I was able to work for difficult clients.
This became part of my portfolio, and of my reputation. This is a bonus skill I acquired that really gilds my expertise on the matter.
Here are a few thoughts on some selected portions of your question:
When he messages me in the night I only get them the next morning and I remind him of my availability hours ...
Don't remind or comment, just do not be available and communicate the bare facts the next morning, as if everything was totally normal.
If he'd criticize you for not being available, tell him something like "I am available now, let's talk."
If he insists on talking at 3 a.m., tell him that you don't - or be available and bill him with a x% bonus on top of your daytime fees (calculate that bonus so that it really makes it worthwhile for you to work at these hours, and sleep in on the following day), which - of course - you state in advance, but as a fact, not as a question, with total naturalness.
If communication improves when talking at 3 a.m., propose only such times in the future. This might have the paradoxical effect of him asking for proposals at "usual" times.
Background story: I have been working with a client who would write long emails at 2:30 am and even later, but never during daytime. I found out that he was very busy during the day, slept for 3 hours between 10 pm and 1 am, got up and worked til 5 am, then went to sleep till 8 am, then went to work. He did that 7 days a week for the last 25 years. He was a very successful person and told me that virtually all of his successful ideas came to mind between 1 and 5 am, while during the day, he just did his routine-tasks. Our cooperation was no routine-task for him, and he didn't expect me to reply at 2:30 in the morning.
... and seems to have a disregard for any professional opinion I give
How do you come to this conclusion? What exactly is he doing or not doing that lets you know it is disrespect and not something else?
It seems like no matter what I do, it's not good enough.
Again, how did you arrive at that conclusion?
In my experience, it is vital to reflect your responses and interpretations when working with so-called "difficult clients" or "clients from hell", as a business-partner used to call some.
Some people do not communicate appreciation at all, some in ways that I would never have recognised as such.
Make sure to really understand in the beginning where the client wants to go. This is the basis for the contract. Seems that you did that.
For example, one lady would always find and call at least 3 "failures" in the work I presented. When I outright asked her to rate the results I presented in relation to the goal she had communicated as basis for our contract in the beginning of our cooperation, on a scale from 1 (no progress towards goal) to 10 (full progress towards goal), she replied "8 to 9", which was frankly more than I expected, because we were not there yet and there were future milestones to be accomplished. So I thanked her and when I asked why she criticised, she said "Well, on the level on which we are playing, this is part of the game."
That helped me understand: I started to criticise her criticism, and she enjoyed that immensely. She reduced criticising my work to a point where she eventually stopped doing it completely, so I challenged her: "Is there something wrong with my work, because I don't get the usual feedback from you any more?" No more difficult client from that point onwards.
So, ask to assess his idea of quality: "How do you rate my work XYZ in relation to the goal blah blah blah from 10 = full success to 1 = zero success?"
If you get a 3, thank him and ask what he thinks you should perform to be worth the money he is paying. If he says "7", ask what needs to be done to get a 4, a 5, a 6 and a 7, a 9.
If you have such talks, bill them as "performance review" or something similar.
He never pitches so I haven't had a meeting with him in 3 months. I have coped to some extent with one-line emails.
Fine... speak the language of your customer, they say... ;-)
If he doesn't provide information necessary to continue, just tell him that. Link it to his goal that you assessed in the beginning:
"Are you still interested in having completed X by February 1st?"
"Yes, of course!"
"Good, please provide A, B, C no later than Z in order to make that happen."
no answer until Z
"As I didn't hear from you, I put X on hold, Please let me know how you wish to continue. In case you want some options to choose from, let me know as well.
To keep your slot open and have you on priority in relation to other clients while not working on X, I will charge a reduced rate of $M per day."
Please feel free to comment, I'd appreciate it.
I think this could be a client to learn from :-)
