Stabilize with least amount of filtering

edit: see next post

I've got a problem with concatenating transformations between the tracker and a transform tool.

I have stabilized some footage using the tracker's "BG only" and "Start & End" settings with intermediate points to get a smoothed plate instead of a total stabilization. However, black edges are creeping into frame (of course) and I want to add a transform tool to scale everthing up a tiny bit.

My problem is that I want to do this with the least amount of filtering and apparently, the Xf doesn't concatenate with the Tracker: changing the filter in the Tracker to nearest neighbor makes this obvious. The image will degrade no matter what the Xf tool's filter is set to. With two concatenated Xf tools, the filter setting of the first one is ignored.

So, I thought I would just use two Xf tools then. The first one connected to the Tracker and the second one for scaling. However, this doesn't work because there's no "Steady Angle" output. Using the unsteady outputs and inverting the transform won't work either because then I wouldn't benefit from the Tracker's smoothing...

What's the best way to tackle this?

Ok, so I might have overlooked some stuff... I've connected a Transform tool to the tracker's unsteady inputs and they actually ARE affected by the "Start & End" setting. So after connecting the inputs, enabling "Invert" on the Xf tool will do what the tracker would have done.

However, when I add a second Xf to scale the result up a bit, both tools' filter settings affect the result. How do I know that there's actually concatenation of transforms?