It's a bit hard to see how this RCT trick could be useful for reducing anything besides the number of gliders.
RCT is basically one very unreasonable end of a wide spectrum: you can use a very small number of gliders to build something, as long as you're content to have the construction take a ridiculously long time. Conversely, you can build that same thing in a lot less time, but it will take a lot more gliders.
That's definitely completely true. We can specify the relative positions of the initial gliders at each of the three corners of the RCT pattern in just a few dozen bytes.
But the number that says how far apart those corners are from each other has very roughly half a million digits. The exact number depends on exactly what pattern is being encoded by the RCT pattern -- I think the example construction of Alan Hensel's decimal counter pattern needs somewhere around a 450,000-digit number.
There are some optimizations underway to decrease that number by a few percentage points, but it's always going to be a very big number!
RCT is basically one very unreasonable end of a wide spectrum: you can use a very small number of gliders to build something, as long as you're content to have the construction take a ridiculously long time. Conversely, you can build that same thing in a lot less time, but it will take a lot more gliders.