You might suggest that he use vang sheeting. Normally the vang is not used for upwind work, but you "can" use it to set the twist which is the typical main sheet function. Then with the twist taken care of, they can use the main sheet for angle of attack which is what the traveler usually does. With this usage, the old traveler is just a centerline anchor point for the main sheet and does not need to move.
I have a friend with a C34 that has been sailing his boat this way for years due to the bearings in the traveler car being toast.