Purge heads on dual head printer  

Purge heads on dual head printer

Hi everybody

I'm using a SOVOL SV04 with dual head (IDEX) configuration. 

During dual extruder (dual Material) printing there is always one extruder in park position. Immediately after printing one material the extruder moves to park position,  until it is cooled down, there is still some filament leaving (retraction won't stop this completly). 

This filament is then missing at the start of the next layer. In Cura I did a purge tower allowing me to "prefill" the extruders. Prusa slicer does not allow purge towers in dual head configuration, therefore I would need to find another solution. 

Question: has anybody an idea how to setup in Prusa Slicer a "prefill" of the extruder before it is printing the next layer of the part? This could be just extruding some filament before leaving park position or something similar.....
I had already the idea to place a 2nd part on the bed which represents the purge tower (in fact I would need to design it individually for every print), but then I would need to tell the slicer to always start printing a next layer on this "purge tower" before moving to what I really need at the end. Would be an acceptable solution for me, but how to tell the slicer about this priorities?

Appreciate your help!