Use the clear of either Monokote or UltraKote. On the bottom only will stop air transfer.

However if you lost both ailerons there is another problem:
1. Were the hinges glued in properly? Earlier this year while helping a new pilot both ailerons parted company from the wing. It was blamed on bad hinges (plane was landed safely using the rudder). Later in the year found that he was glueing into one surface and then inserting into the other. This WON'T work with CA hinges as the second part won't glue plus the glue will harden the hinge too much and cause it to break.
Or
2. Were the linkages installed with no slop or play and with adequate tork servos? I have seen alierons part company of a wing on a 40% plane with less than stellar linkages. You can't use the hardware designed for a 60 size sport plane for this kind of aerobat.

Hope this helps. Ask more detailed questions if needed.

EXCAP232