I was looking to do the same thing, but to preserve the list as a just an array of strings so I wrote a new code, which from what I've been reading may not be the most efficient but worked for what i needed to do:
combineListsAsOne <-function(list1, list2){
n <- c()
for(x in list1){
n<-c(n, x)
}
for(y in list2){
n<-c(n, y)
}
return(n)
}
It just creates a new list and adds items from two supplied lists to create one.