I think there are much simpler solutions... yes - I think there are indeed!
If the NPC is the cause of my problem, then the solution starts here, and certainly not with additional items.
My suggestion: The moment I, the player, ask the worker NPC for a BOD, he should offer me whether I want a small or large BOD. So he should give me the choice of what I want to work on. The bribing of small bods on Exceptional should also be left out in any case, because it takes the gold out of the game again. Vet-Rewars.... all well and good ... and if something like that comes, from which year will it be available

... 1 year, 5 years or only after 10 years? As a player who always wants to get started with my project straight away, do I still want to wait for a reward? Not really, do you?
I need to disagree.
Yes, Large BODs are a pain to get, perhaps, their spawn rate could be increased a bit but to give to the player the option to decide whether to be handed out a small or large BOD I see it as too much...
I prefer it to stay random and let the RNG decide.
Maybe, what could be introduced is the ability to turn in to the NPC a significant number of small BODs in order to be handed out a Large BOD of that type ?
One problem with BODs and their storage, is the large accumulation of small BODs retrieved in order to try to get Large BODs.
The banking of points was thought to address this issue but, unfortunately, at least to my opinion, the banking points given are so low, that most players, to my understanding, do not bother with the points banking system and they just claim BODs a go-go piling them up....
I mean, burn the resourcs, fill in the small BODs over and over and over with a great expenditure of time and resources and this to only accumulate a few meager banking points ?
No thank you.
May UO players much rather prefer to keep claiming BODs and pile them up on some vendor untl they get those Larges to use their enormous stock of small with...
Either the banking points should be seriously increased, and I mean
seriously, or, in addition to banking points, it could be added an exchange system whereas, if a player offers to the NPC, say, one of each small bod needed to fill up a Large, (for example, 1x platemail small BOD for platemail gorgets, gloves, helm, arms, legs and tunic, that is, 6 small platemail BODs of the same likewise quantity and type, whether normal or exceptional as well as of the same material), the NPCs would take and delete those 6 small BODs and hand out a Large BOD of that same type, material, quantity and quality.
The player would now have a Large BOD and still need to use another 6 small BODs to fill it up...
This way, I would hope that, over time, the large stock of small BODs sitting in containers or on vendors would slowly reduce.