All credit goes to original mod creator Mpstark. I just updated the script to Next-Gen.
Description:
Small tweak that allows for fast travel while mounted on Roach, which is a little bit more lore-friendly than Fast Travel from Anywhere. The same disclaimers as that mod, you cannot do it in combat, and you shouldn't try to Fast Travel during the course of a quest, as this can
break the logic of some quests (however this risk is greatly minimized, since most quests that break are indoors).

I highly recommend installing Smooth Mouth and Dismount (updated version for 4.03 in comment section). It fixes the game using the wrong camera after fast travelling from Roach.