I started a new char for Dragonborn and ran her there at level one. I did this by completing BFB letting Faendal do all the work, then hid in the tower during the dragon attack. I was in Ivarstead when the Cultists attacked, so again I ran and hid while Faendal and the guards made short work of them. In this way I arrived at Raven Rock as a true level one. In BFB I was lucky to find a couple of pieces of armor of the squire, so my modified light armor skill was 45 or so, but other than that I was wearing hide armor and shield, hunting bow, and smallsword (from the JaySuS pack). The game was set to Expert difficulty.
I stuck with ranged against the ash spawn outside the gate. With Faendal and the guards, they fell quickly, although the miniscule amount of damage my shots did relative to their overall health was a bit troubling. After that I ran through the woods along the coast in no particular direction. I was surprised by a couple of ash hoppers, and this was my first real fight as a level one, since I had to face them at melee with no guards. Ultimately I dispatched them, but I did make use of a tactical levelup. After that I saw a ship camp on the beach, and decided to investigate.
A bandit was standing in the gate of the camp, and I took him out with two shots. "Hmm, these guys don't seem that hard" I thought, and charged in to attack the rest at melee. What I learned here is that the random bandits use regular level tables, so the underlings were all in my range. The reaver in charge of them, however, not so much. He came out and walloped me down to about 5% health. I ran like the dickens and chugged potions. Then I approached him more circumspectly. He had a big two-hander, and I think the extra armor protection from my lucky finds was all that kept him from one-hitting me. However, he was also very slow because of it.
I found that I could block until he swung then bash him, and while he staggered I could hit him three or four times. So it was "Blooooock . . . Bash! Swap! Swap! Swap! Blooooock . . . " etc. If I mistimed the block and he hit me, I was again down to just barely alive and had to run and chug potions or cast healing. This happened a few times (I started off with about 20 minor healing potions and had none left by the end). Remember that this whole time Faendal is off to one side unloading arrow after arrow into the guy. I was also able to benefit from two tactical levelups (so I entered the fight at level two and finished it at level four). During one of my terrified sprints away from him when I'd mistimed a block, I ran into another nest of ash hoppers. One of them attacked me and I had to fight it off, but the other attacked the reaver, which in the end helped out a lot.
So anyway, yeah, that was doable, but not easy by any standard. This character is now at around level 20 and has progressed to the point of rescuing a certain Nord village, learned a couple new words, and found two Black books. None of the fights have been as hard as that first reaver though. I highly recommend it if you have patience and love a challenge, but I highly recommend against it if you just want to get through the content.