Quad specific stretches

fss-se22 and fss-se23 give me most trouble. My quads are made of stone. Are there any specific quad stretches I could add to the routine to progress more in this area? 

 

My hamstring mobility is way better than quad, so I'm looking to balance front split stretching a bit. 

 

Thanks, Peter

You can just repeat ones in the series ideally adding depth with each round.