WOFF UE custom settings for the D3D8.DLL file
About halfway down this pagehttp://www.thatoneplease.co/toolsWOFF.html
Is a good insurance against losing pilots and settings when trying out various installation's and mods.
I'm away from my pc right now so someone else might confirm before I can, but the hat in the ring install points to your WOFF folder automatically. I think the easiest thing to do would be to install one WOFF instance. COPY the whole folder onto your external drive with a different folder name (OBD1 maybe) and then install HITR over the original default folder. Then move that one.
Please let someone else confirm before you do this. I know it works for Rome:Total War but I haven't tried it with WOFF