Regarding boarding, the Bloodfist had means to from above. The retractable planks also doubled as a means of boarding other ships or unreachable settlements, as well as provide a means of allowing trade or hauling to occur in a more secure manner than from the more vulnerable bottom deck. Plus, what if ground-level cargo transfer is not allowable (terrain or a law, or how a settlement/keep/dock is built)? Well, the mid-upper deck's planks are still a means, and reaches far enough that the wings/props won't collide with the nearby building/tower it would have to dock with.
Regarding a landing gear, in case asked or advised, it was implied that front legs were retractable on the frontside along with retractable wedges and/or wheels like you see on a catapult that are on strong reinforced hardpoints on the bottom-most deck. It would also be implied that the bottom-most deck would have (a series of) metal paneling to minimize friction from slowly to violently shearing off the bottom deck of the ship when landing or taking off. It would also reinforce the flooring of the bottom deck as well to make it not as scary as the ship ages (after all, wet storage tends to be placed in there, as well as plenty of heavy wagon and personell traffic going through there). It applies to both the Bloodfist and it's descendants.
EDIT: (31.19 related)
I'm acquainting myself with .19 right now, and I'm trying to get used to how things work again (been awhile since I last played any DF). Also, this is the first time I've dug deep to find magma. Found water so far (-41z from top shaft floor -1z from gateway floor), and a fungrest. My finding of the cave system appeared over water, and I capped the stairway ASAP, seeing as a cave croc was right below. Who knows what else would be waiting for me? A security checkpoint has been made with only 1 access point into the watery caves (should be more than enough, and a floodgate will provide protection or buy time to build a wall, just in case). Another shaft will be made near the checkpoint, and have a similar build when I find magma (hoping for less z-level separation for the next stage, and hopefully, minimal fiend activity). This makes good practice for when I eventually get around to the project. I'm also attempting to make heads and tails with the whole pottery and clay feature, and find a way to keep the clay (loam) separate from the rest of the rocks, outside bookkeeping, dump clay stock, reclaim post-dump at a designated pile. I'm hoping for a fix for that; the other features like proper livestock and such, nests, hatcheries, I'm slowly learning as well with some help from the wiki to make full (proper) use of them.
EDIT EDIT: (ditto above)
dug far deeper for another 100z minimum to find another similar cave system, but found adamantine, which led to both a magma sea and an adamantine pipe that goes through. I think I made it to my limit for now in exploring first hand. Now I gotta establish a fort that'll last at least a few years (supply and etc.) before I can have any confidence at all to get around to splitting work, setting jobs and so on. I'm waiting for a lazy newb pack, or at least the tools I used last time that helped the most with management to be updated to .19 (or whatever later editions get released) so managing at least the work should be easier to work with. Borrows seem more temperamental than I expected it to be. If I get enough of the ship done and a good hang of it, I might set a burrow exclusively ship-side, for both security and construction reasons, and the hauler class should keep them supplied. Provided I wrap my head around the burrows thing. It can really help with dedicated construction portions when building the ship.