Are there any worries about "stepping" the mast on water. I know the mast is easily handled by just me.
I sometimes launch where there is a low bridge between the launch ramp and the ocean (Puget Sound, actually). The passage under the bridge can be quite narrow depending on the tide. Thus, for a typical launch there I take the TI off the trailer, leave the amas folded in, lash the sail to the hull/folded akas, paddle out a few feet to get enough depth to insert the drive, pedal under the bridge (usually sitting way to one side to make room for the mast), continue pedaling to a beach, then getting out and stepping the mast & rigging the sheets.
I never "worried" about it because there was no other way that I could see to do it. It is a pain, especially when the TI is bouncing in the small surf and the mast is blowing in the wind and I'm standing in 3 feet of 45 or 50 degree water.
I agree with Nohuhu that the best way is to step the mast on the trailer: "The mast/ rigging and everything else is Installed and tested on the trailer, where they are easy to reach and no stooping is required. Gotta love that."
But it works either way -- a tribute to the simplicity of the Hobie TI.