If I may pick some views to answer a question regarding base tape.
The base tape is the weakest link in the reusability of a tub. Once the tub comes off, so does most of the base tape. I tend to remove the base tape completely off the tyre. So far I have been replacing the base tape with tub tape.
What are alternative solutions to replacing the base tape?
Not in my experience at least not with a well made tubular such as Veloflex, FMB, Vittoria and the like.
Often basetape is put on at the factory using a liquid latex sollution.
I know latex based wall to wall carpet glue to work as would Barge rubber cement.
It's definitely not a good idea to use rim cement to stick basetape back on as next time you remove the tubular there's no telling whether or not it will stick to the tubular or the rim...
No idea what tub tape is though.
Oh, when you remove a tubular, only pull the first 10cm or so off the rim then lift the tubular off by pulling it straight off not sideways. That way you much reduce the chance of the base tape separating from the tubular's casing.
New base tape can be bought but surely you can avoid having to buy it in the first place?