Hi Don,
When I set up my first v3 with 20v on the finals I set the bias as Ashhar defined a 100ma increase when pressing the PTT. My yl mainly uses digital mode as yours but we have about 2-3x the heat sink, mainly they have longer fins than yours. Behind that is a 70-80mm fan with a printed shroud over it. Nothing gets warm. The unit that is on my side of the room has a scrap,  isolated 1x1x18" aluminum angle iron maybe 6" long attached between the two PA transistors. That bolts to inside of the aluminum case. I can hold the key down for some minutes before anything warms up. I have added heat sinks and fans to some other units with mixed results. A little air movement really helps at some risk of electrical and or audio noise.

I have wondered too about the bias but we get good audio reports with the stock setting. Should it be higher or lower 

Have to ask about the quality of the transistors. Were they gotten from a reputable vendor?
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73
Dave
ADOB
Raduino bracket and Ham_Made_Keys