I just thought of a solution and probably writing a own %job_topOpt.frd file would be the best. The extrapolation of elemental values to the nodes is possible within my script. From that I might create this frd file. To have a nice possibility of clipping legend-values, the request regarding a feature in prepomax would be similar to this one:
https://prepomax.discourse.group/t/transparent-plot/1392
Best regards,
Stoli
PS: I am working on the code, to be published on github asap