70-75 is a good temp. No reason to go much higher unless your just wanting to help the utility co. out
Main thing is to have the metal STABILIZED at that temp.
70 is the "magic" number and any time your shooting below it those planets seen to have alot more alignment issues I've found.
I'd shoot the first coat "straight" and on a TEST PANEL
Just incase "Their Baaaack".
I really don't see the 10% helping that much outside of helping it to run easier.IMO.
Beds are a major PIA to shoot and runs are going to be high on your list of things to avoid.
One other thing. WHAT clear are you using??
IF it is the Nason Selectclear 497,
Better reread the mix ratio.