1st, I agree with the above suggestions to speak with an attorney, preferably the one who drew up the trust for your dad (if he/she is still around) or at least that same law firm.
Do we have to wait until ALL the properties are sold or the whole thing is liquidated before we split it? Or do we split it up as we go?
I don't see any guidelines in the Trust itself.
Again, if the trust does not specify, then you wont be breaking any portion of the trust. Without reading it myself, and I am by NO MEANS a lawyer, but I can read!...if, as you say, there are no guidelines, then sure. Liquidate a portion and split the proceeds.
An estate attorney told me that a trust is just that - a trust. The Originator - the "Trustor" is hoping that his desires will be followed and the trust is a legal agreement between the involved parties that helps that along, but if you two are the only ones left......well...then there's no one to contest anything if you break the trust or go against a provision. After all, if you and your sister agree, who is going to be harmed?
B U T ...
Talk to the folks who drew it up, is what I would say.
And FWIW, it's fine to ask such questions in here, but taking specific legal and financial advice from an internet forum populated by people who are complete strangers to you is never a good idea. Same as taking medical advice. What you should hope for is basic guidance, and I think you have gotten that so far.
Best of luck, and my condolences on your loss. My dad has been gone since 2000 and mom since 2014. It's not easy, but it does sound as if your father was forward thinking, and that's good.
Take care and be careful.