What brand of toilet paper can I use in my TT?

Any kind you want. It does not have to say septic safe.
There are many posts showing the dissolving times and most brands dissolve in less than a minute or so.
Many of us full timers use a quite a bit of water when we flush and don't use chemicals either.
We full timed for 11 years, used whatever toilet paper we (actually wife) liked and never had a problem.