You pretty much have the right idea, just a couple of notes:
1. Joe Buyer should NOT be the trustee. The trustee should be someone else that Joe Buyer chooses (could be a lawyer or a very trusted friend). The trustee should have a different last name and preferrably lives out of state.
2. Warranty Deed transfers property ownership to the Land Trust (not the trustee). The trustee is the legal guardian of the Land Trust. Once the property is in the Land Trust, then the beneficial interest in the Land Trust is transferred to Joe Buyer.
Nobody needs to see the trust agreement unless absolutely necessary. DO NOT record the Land Trust - that would defeat the purpose. Only the transfer of the property to the Land Trust is recorded so that the owner of record becomes the trustee.
By law a bank can not interfere with the transfer of a property into a trust. This mean that they can not invoke the "Due on Sale" clause just because the property transferred.
Successfully executing a sub-to deal is VERY complicated and involves a ton of paperwork. I have done several of them and I am comfortable with them now, but the first couple were a lot of work to get through because I had to learn as I went.
I am sure there are several courses on the market that teach this technique. The one that I use and I have been very happy with is The ABC's of 'Subject To' at http://www.getthedeed.com.
Good luck.