I ran stock springs with AGX struts (full soft front, full hard rear) for years in RallyCross to good effect. Car was fully stripped, and even with the stock springs ran a good inch higher than stock ride height.
I'm pretty sure that a call to Bilstein would allow one to find an HD insert that could be made to work with the car, then add some coilover sleeves like GCs and then you can pick and choose spring lengths and rates.
JVL is who he is, and that's all I've got to say.
For the stage rally SE-R I'm building, I have a set of the inverted Hotbits, but it would be really hard to justify a set of those just for RallyCross.
Stock SE-R front control arms are pretty strong, relative to most cars. I've never bent one in years of rallycross and using the car for stage rally opening. I would be hesitant to beef them up more as the damage might just migrate to the mounting points on the body, and those are a lot harder to swap out than a control arm...
The rear arms, on the other hand... I'm going to build my own tubular arms, maybe even over this weekend. Less effort than pressing the bushings out of the stock ones to install the ES bushings I have on the shelf . . .