It seems to me it's time to take a step back and get to grips with the fundamentals....
So you have a nice route along country lanes, that is 200.1k.
That would make a nice DIY audax.
Firstly, normal 'Advisory' routes...
So, decide on some controls. Perhaps at the 4 'corners' of the loop.
Put these controls into Google Maps Walking, and see what it comes up with.
NOTE this is not the route you are planning to ride; it's a route you *could* ride, even if you have no intention of doing so.
It might take busy main roads, and canal towpaths.
This is the Minimum Distance Between Controls.
So if this comes up short, it's no good.
Because the validation is simply that you passed through the controls.
You *could* have taken the busy main road and the canal towpaths.
Your passage through the controls does not guarantee you did the 200.1k.
So you need to adjust your controls, or add more controls, to make it so that the Google Maps Walking cannot short-cut it to less than 200k.
Once you have done this, you are free to ride your intended route, so long as it passes through the controls.
You don't need to take the busy main roads, or canal towpaths.
This usually means that your planned on-the-road actual distance will be greater than the Minimum-Distance-Between-Controls, because you won't be riding the busy main roads, or canal towpaths.
There is an element of skill in designing a route and controls to avoid on-the-road overdistance versus the Minimum-Distance-Between-Controls.
And onto Mandatory Routes...
Now, if the route is so twiddly that you are having to put in dozens of controls to force the route to be >200k, then that's when it might be appropriate to use the Mandatory Route option.
Rather than specifying an Advisory Route with 20 controls, then it might be easier to just say "THIS Route, goddammit!"