Since there is no answer I will show how to make a random unit:
If you are not ready to have your mind blown go to conclusion at the end.
Take a 3-clock unit and set an output somewhere, now since this is only 3-clock it's gonna burn at RANDOM place so the output will be random. Like this:
Now you probably don't want it to change so much but only when it stopped, well.. idk if anyone used it(probably used), anyway I've made it my self, I call it "signal cuter" the point is to split the signal into 2 signals: first contain odd number of "not gates" and the second even, and then merge them into "or gate", the result is: when a signal is sent, it's gonna stay as the output until the second path will cut the signal and that way no matter for how long you set the input to "on", the output gonna be "on" only for length(second path) - length(first path) "ticks".
in this example, all signals that are more then 3 ticks length are shorted to 3 ticks long. On same property you can make a "signal protector" also made by me :), it's not passing signals less than X long all the difference is that both paths first and second need to be odd length and the X is equal to length(second path) - length(first path), but the signal become shorter then the original signal length. Example:
FINALLY the conclusion: so now you can take the a 3-clock and to chain it with the "signal protector" with X=2 and THIS WILL BE STABLE!! It won't throw junk until the 3-clock burned and the result is stable, the next random will be generated after the next 3-clock burn, if you want to make it faster just make many units of that.
THE RESULT:
It's still throw junk in "Redstone Simulator" but in "Minecraft" this works great!
Please if you're passing on this technique, leave the names "Signal Cutter" and "Signal Protector".
From what I understand, you have something like this:
Teal is the two T Flip-flop, red is the mechanism modifying the state, and purple is the resulting output. In all the examples, the right T flip-flop won't be outputting a signal and the left T flip-flop will be outputting a redstone signal.
Wire ON/Torch OFF
Rather simply, a switch can be put in place to force this wire ON and the torch OFF.
Wire OFF/Torch ON
The pistons allow the T flip-flops to continue transmitting power to the output. When the switch is flipped off, the pistons retract, causing the line to disconnect and the wire to be in the OFF state, and the torch to be in the ON state.
Best Answer
Since you apparently don't want moving parts (which eliminates solution 1 and 3) and being able to send a signal through both wires at the same time is a case that can happen (which eliminates solution 2), I worked out yet another solution.
Like the first one, it's 4 wide tileable for 2x2 wires. The idea to this is actually pretty similar to the first one, I just let the wires go around each other while avoiding that they power each other. The piston was an easy way to do that, since it can go down without going forward and only one redstone wire of the other path had to be replaced with a repeater to avoid problems. Without the piston, I had to use more repeaters and some clever wiring.
Here is a screenshot of all eight lines that you need:
Since that's not very helpful for rebuilding, you can download the structure file here*.
The odd numbered (counted from the left) columns have one redstone tick delay, the even numbered columns have three redstone ticks delay. I tried to switch one repeater over from the even numbered column to the odd numbered column, but that didn't work, because all three repeaters on the even column are there to avoid power overflow between the two lines of the even column. If the difference in delay is a problem, you can fix it by just putting two repeaters on first setting in front of the even numbered column lines.
It's 8 blocks long, 5 blocks high and of course 4 block wide for 2x2 wires, which makes it more compact than my first solution, but there are less air blocks, so you actually need a similar amount of material:
You need 28 redstone, 8 repeaters, 1 slab and 42 blocks that support redstone on it, some of them have to be solid, so you should build it all out of solid blocks to be sure, except for the one slab of course (that's not included in the 42 blocks).
This design works with pulses of any length.
Late edit: You can replace the repeater in the odd top input->odd bottom output line with a piece of redstone dust, but since that makes the delays even more varied, I won't edit that.
*That file is on my Google Drive, but it shouldn't get deleted. If I accidentally delete it, contact me (contact details on my profile page) saying that the file is in my October 2017 backup and link this answer.