It's unlikely that 5 stitches will make that much difference. You could just decrease evenly up the sides of the second panel a couple of times--a stitch on each side and then once again on one side. This way you'll know the tops will have the same number of stitches.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry