RE: How dumb would it be to start flying a PTS without a trainer?
Trust me that if you try it on your own your progress will be sllooowww. What with all of the repair time and all that.
Do yourself a BIG favor and join a club with an instructor. Any associated expenses will be recovered in money saved on repairs.
OK, Just WHY do you want to do this on your own? No clubs, no money or too much macho ego?