Hi Lissa,
I'm in late tonight, so this may be a bit of a rushed reply.
I think one of those Thomas SMITH deaths is likely to be your man. I am confused, however, that I can't turn up a burial.
I don't know how well you know the area, but it has what were called "strip parishes", because they were very long and narrow. A parish map looks almost like a piece of streaky bacon, with Aston Clinton (which includes St Leonards), Buckland, (which includes Buckland Common) and Drayton Beauchamp parishes all stretched out side by side.
This make it very hard to know where an event may be recorded, as you maybe have to travel 5 or 7 miles to get from one end of a particular parish to another, but maybe no more than a mile in the other direction to cross all 3.
Dancers End, (where your SMITHs are in 1841) and nearby Ebbs Pitt, (where mine are), are tiny Hamlets - the latter barely exists today. I'm not even sure which parish they were in, back then.
(They are not street names, rather small groups of houses, surrounded otherwise by countryside).
Within those three parishes there are 4 churches, (Aston Clinton has it's main one, but also one at St Leonard). In my experience a baptism, marriage or burial can crop up at any, even if the people were not in that particular parish at the time. (A complication is that St Leonard was debarred from performing marriages from 1754 to about 1860 as a result of Hardwicke's marriage act).
I have the wherewithal to check registers for all but Drayton Beauchamp, and didn't find a Thomas Smith burial. That may mean it was at Drayton Beauchamp - it's hard to imagine why he might have been buried elsewhere, particularly as his wife stayed put in the area.
If you don't want to spend out on Sarah's second marriage certificate, I can let you have the full transcript from the Aston Clinton parish registers, if that helps. Just let me know.
Oh, and by the way, the 1841 census does not give place of birth - only whether born in the county, or outside it. Thomas SMITH is from outside the county, like his wife, but that's all we can know from the census. (People who can't stay alive until 1851 are most annoying!).
I have to say, I think it unlikely we will easily establish a connection between my SMITHs and yours.
If your Thomas was born out of county, and his wife was Oxfordshire born, there has to be a good chance that so was he, I'd have thought.
But you never know, in this game.....
Stef.