Don't underestimate how your imagination can fill in the blanks. Even if you can't draw a complete walk cycle frame by frame, you still know how it looks like when a person or thing walks if you've seen it before. Of course you might break the illusion if you look at it too closely, but you don't have to do that. And early on, it doesn't even matter if you can't see what happens too well. If it's some shape that is your tupper and it's moving then hey, guess what. You're visualizing and practicing, you might not see everything perfectly ight off the bat.
Open or closed eyes, which one is easier for someone depends on the person, but I think it's a good idea to practice using both methods. And I'm definitely the kind of a person who enjoys touching things with my hands so feeling the tupper has always helped me. As did reference images, it's much easier to remember something you saw than to create an entirely new one. I made a quick sketch of the tupper's form early on from as many sides as I wanted and every time I felt like I was losing it, I could just remember one of those. I could look at him from many different angles and even though at first it was pretty choppy, it got much better as I practiced.
Oh and because we're talking of movement, maybe you should try moving yourself as well. A bit difficult to look at the tupper that way, but you might learn to see what is around you as you run through the landscape. That helps me immerse myself well at least and it's visualization in the end. You might learn something.
Also I noticed how you said something along the lines of ignoring your own doubts and such. If you remember my absence of disbelief tl;dr I wrote way back, I did say that outright ignoring things is stupid. Mostly when it comes to responses you think might be from a tupper, but it also goes both ways. Don't ignore your own doubts. They're caused by something and ignoring them won't make the reason go away. So think about the causes and see what would ease your doubts. Of course, if you think that the only way for your doubts to go away actually first requires you to deal with your doubts to get there, you've createn an impossible situation. So think how much you really need instead of asking for the impossible.
I've seen plenty of people who say they will do all kinds of cool stuff when their tupper is imposed, but until then they think they can't do anything. I don't know why that is, seeing how there's a lot of tulpas people spend time with that aren't imposed. You might only be seeing your goal when the journey there is also pretty important and it can be fun, of course. And should be. You don't need to see a person to have fun with them, nor do you have to actually talk to a person to have fun with them. Of course it's usually more or less only one of those you can do at a time, but well. Those who are deaf and blind still manage to have fun with others somehow.
If you only like a few things and you think you can't share those hobbies with someone else (the tupper in this case), then how about getting new hobbies. Oh sure, "but I don't care about anything else!/I can't do something else!". Once you start doing only one thing and being lazy, it starts to look really hard to actually do something new. Feels impossible. Often happens to people who have been unemployed for a while and basically do nothing but sleep and eat all day. It becomes very hard for them to actually motivate themselves to do something, but once they try, they might see it actually wasn't so bad and it's fun. A person who never tries to do new stuff or never wants to change will stagnate and grow stubborn in a bad way. It's not a pretty sight, believe me.