4 words:
Go read Twilight 2000 (Both Versions)
...That's 6 words though.

Anyhow.
Twilight 2000 is the type which they called "Simulationist Rules" of which on the Spectrum of TRPG rules is like "Simulationist-----DnD-----Freeform."
TW2K is a good example of how something that's seriously complicated to the point of wanting computers to calculate, in an era that didn't use computer for these stuffs, moved onto the next century and streamlined while still trying to retain the simulationist elements.
(Though old fans still hated it for being "not complicated enough".

)
You're doing Simulationist ruleset. Looking at how people streamline that might give you an idea. v=3=v
As for finding players... Weeeeeeeeeell, looking at the previous way you did it......
No you don't. v=3=v
I mean, when you did it you:
1) Did everything important on your own.
2) One player disappeared.
3) The other was phone-gaming.
4) You said the other players didn't require to do the calculations anyhow.
... Now, the roles of the playtester is the basically "mess the game up as much as possible, so that you can know what doesn't work and what needs more refinement"
A playtester that doesn't need to look at the rules is, for all purposes, useless.
You just want a bunch of "sounding boards" to know that you've done something. Now that is
perfectly understandable. I was like that 20 years ago too. And nobody liked their life's effort being picked on too. I also get that. (I still remember how pissed off I was when my playtester messed my game up... But then that guy's a troll who was doing it intentionally cause he didn't get to munchkin everything so... The memory that he tried to run his own new thing with similar theme right after me and couldn't even get out of camp was...

)
Yeah, train an AI player. If you think the last playtest was okay then AI players are enough for your purpose.
But if you really want your players to get your rules... That way you are doing right now is still crap.
Streamlining.
Presentations.
Explainations.
Sequences.
Formats.
The guts to trash some ideas, some of which are precious "at this moment"
etc.
There are so many things to do when making
anything. And it's literally a forever work. Why do you think established systems all have multiple versions? Even FATE have versions and its literally a "talking-game".
And right now your biggest problem is step one: getting out of your own head.
That's essentially the first thing you need to do, if you're
seriously wanting others to care about what you do. v=3=v
Without this, everything else would be stuck.
Finally,
It is okay for you to make your things alone without input from anybody else.Most DIY-guys eventually do that, alone or with friends-only.
I am doing that myself, cause I'm just one of them who couldn't get players even if I tried. (Tried it here 3 times. No answer. Whatev'. v=w=v )
What's the problem with that?
I do this because I like doing this.

That should always be enough.
If that's not enough for you... Welllllllllllllllllll, you sure you're doing what you want?