I always use 30 minute epoxy finishing resin on the center reinforcement. The long cure time allows the resin to be absorbed into the sheeted surface insuring a strong bond and allows me to take my time and do a neat job. "Finishing resin" is just epoxy in a thinned down consistency. I've successfully thinned regular 30 minute epoxy with pure isopropyl alcohol but have heard it could weaken the the joint so I avoid it in critical structures like wing centers.

If you use ca it will probably work fine and be just as strong but you will use a lot of expensive glue and the large amount of fumes can be dangerous to your respiratory system if not adequately ventilated. I also doubt it will have as nice a surface as the epoxy without a lot of sanding but I've never tried it.