KableExtra adding linebreaks in columns with long nonwhitespace strings

I have a long string which I want in a table, for instance 100x the letter A (AAA...). I would like kable to split this string into multiple lines if they don't fit in the table instead of making these strings overflow such as shown here.

I noticed kable is actually able of doing so, provided there are newlines or -'s in your string, see for instance here.

However, I would like kable to do this splitting on either selected characters or on any character, so the output result would be this, but I don't know how to achieve this. I had a look on SO and in the kableextra documentation, but no luck. Any suggestions?

Below is a chunk to play around with.

---
title: 'rasstasrt'
sansfont: Calibri Light
output: pdf_document
---

```{r setup, include=FALSE}
library(kableExtra);
library(dplyr)
knitr::opts_chunk$set(cache = F)
```


```{r}
dt <-tibble(Items =c("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAaaaaAAa", "Item 2", "Item 3"),
            Tmd5ext_1 =c("Lorem ipsum  "),
            Text_2 =c("Duis pos "))

kableExtra::kable(dt, "latex", booktabs = F, col.names =c("Item", "Short Title", "Veryong Title"))  %>% column_spec(1:3, width = "5cm", )
```

You can leverage the newline character in latex, \\ and the argument escape = FALSE in kableExtra::kable(). Settting escape = FALSE causes the \\ to be read as newline characters instead of literal \\. Note that because \ is an escape character in R, you need two slashes \\ in order for R to interpret a single slash \, so to get 2 literal slashes \\ you need to put 4 \\\\ in the string.

---
title: 'rasstasrt'
sansfont: Calibri Light
output: pdf_document
---

```{r setup, include=FALSE}
library(kableExtra)
library(dplyr)
knitr::opts_chunk$set(cache = F)
```


```{r}

dt <-tibble(Items = c("AAAAAAAAAAAAAAA\\\\AAAAAAAAAA\\\\AAAAAAAAAAA\\\\AAAAAAAAAAAAA\\\\AAAAAAaaaaAAa", 
                      "Item 2", 
                      "Item 3"),
            Tmd5ext_1 = c("Lorem ipsum  "),
            Text_2 = c("Duis pos "))

kableExtra::kable(dt, 
                  "latex", 
                  booktabs = F, 
                  col.names =c("Item", "Short Title", "Veryong Title"), 
                  escape = FALSE)  %>% 
  column_spec(1:3, width = "5cm")
```

Alternatively, if you wanted to insert the newline after a specific number of characters, you could write a function to do that.

---
title: 'rasstasrt'
sansfont: Calibri Light
output: pdf_document
---

```{r setup, include=FALSE}
library(kableExtra)
library(dplyr)
knitr::opts_chunk$set(cache = F)
```


```{r}
add_return <- function(x, len) {
  # intialize empty vector
  y <- c()

  # start at beginning of string
  i <- 1

  # Break string up into lengths of len
  while(i < nchar(x)) {

    y <- c(y,substr(x, i, i + len - 1))

    i <- i + len

  }

  # concatenate the substrings together with the newline characters
  paste0(y, collapse = "\\\\") 

}

dt <-
  tibble(
    Items = c(
      add_return(
        "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAaaaaAAa",
       len = 5
      ),
      "Item 2",
      "Item 3"
    ),
    Tmd5ext_1 = c("Lorem ipsum  "),
    Text_2 = c("Duis pos ")
  )

kableExtra::kable(
  dt,
  "latex",
  booktabs = F,
  col.names = c("Item", "Short Title", "Veryong Title"),
  escape = FALSE
)  %>% column_spec(1:3, width = "5cm")
```

You could also use regular expressions to insert the return after a specific character string.

---
title: 'rasstasrt'
sansfont: Calibri Light
output: pdf_document
---

```{r setup, include=FALSE}
library(kableExtra)
library(dplyr)
knitr::opts_chunk$set(cache = F)
```


```{r}
regex_add_return <- function(x, after) {

  gsub(pattern = paste0("(",after,")"), replacement = paste0("\\1\\\\\\\\"),x)

}

dt <-
  tibble(
    Items = c(
      regex_add_return(
        "AAAAAAAAAAAAAAAz123AAAAAAAAAAAAAAAz123AAAAAAAAAAz123AAAAAAAAAAAAAAAaaaaAAa",
        after = "z123"
      ),
      "Item 2",
      "Item 3"
    ),
    Tmd5ext_1 = c("Lorem ipsum  "),
    Text_2 = c("Duis pos ")
  )

kableExtra::kable(
  dt,
  "latex",
  booktabs = F,
  col.names = c("Item", "Short Title", "Veryong Title"),
  escape = FALSE
)  %>% column_spec(1:3, width = "5cm")
```

Note that there are 8 slashes in gsub() because the slash is also an escape character for regular expressions, so each literal slash has to be escaped with a slash, but then each slash that is being used as an escape character for regex also has to be escaped again for R, requiring another slash.