Currently, all of my reed valve 1/2a set ups are on 35 foot lines. For example, the vintage performance models Baby Nobler, Baby Ringmaster and baby flitestreak. All are 25 inch wing span and flown with a golden bee or a black widow. More than enough power and line tension. I could do 40ft lines on these, but I'm content with the results.  I think there's a few in here

You can play with the line lengths until you get down to a rotation rate that won't drill you into the ground. But do not even consider using Dacron lines again. Time has definitely moved on--for the better!

I've got a Baby Bee in a SIG Baby Skyray on 42' .008 stranded steel lines--very good trainer. A Baby Clown with Medallion .049 on the same lines--very good stunter. A Lil' Satan with .049 Black Widow on 26' of 30 lb Spectra--which will drill you into the ground, or let you lose the plane behind your head when maneuvering. Whump!

The Divot