You'll have to take the guard off if you want to attempt it with the board in one piece.
1) First of all if the board has much of a warp you'll have trouble getting there.
2) Don't try for perfection, your goal is to get one face flat enought (maybe marginally) to allow it to be down-side when you run it through the surface planer. You might actually have some unplaned surface when you reach the point where you can go to the surface planer.
Trick is set your fence so there will be a small amout of overlap - about
1/4" is enough. Set your table for very minimal cut - 1/64" to 1/32". All of your planing will be done on one side and if one edge of the board is more out of shape, start with that one against the fence. After first pass, alternate with the other side against the fence and vice-versa for a few passes. AGAIN - you cannot achieve perfection and you are likely to have some unplaned areas when you reach a point where the board is flat enough to place your planed surface down on the surface planer. Get the opposite side planed then flip it over and finish the side you started on the jointer.
If you find yourself eating away too much of the board on the jointer, chances are it was to warped to start with.
As far as operation with the guard off, a lot of paranoia will get you through this. Actually with the wider board the entire table is covered. Just use your push blocks and be aware of where the knives and your pinkies are. Also, with the minimal cutting depth, there is less tendency for a push-back. Paranoia!