When I checked mine on my 900 it was difficult but I used a socket and ratchet on the front of the engine.
I can't think of a way to do the valves without seeing the mark other than this;
While turning over the engine, watch for the intake valve to open, go down, and then close, come back up.
As you rotate the engine further the piston is on the compression stroke and coming to TDC when it reaches the highest point, and the power stroke begins as the piston goes back down. In other words you are at TDC (top dead center) and both intake and exhaust valves will be loose, adjust the valves.
On other types of engines I would use a straw and feel for the piston to come to the top on the compression stroke, on this engine you may not want to remove the injector to feel for the piston movement.
So if it feels like you are on the compression stroke and it's hard to turn with the ratchet, try a couple of rotations to get the feel, you are probably very close and safe to do the cylinder's intake and exhaust clearance check. Now do that for the others.
The other thing is doing this you may have an easier time to locate the timing mark. Little patience you might get lucky. Use your wife's white fingernail polish to paint it up for next time.
Just thought of another way; just after the intake valve close, mark the pulley with a piece of tape and note it's location, then keep rotating until the exhaust valve just opens. Keeping an eye on the pulley and tape mark and note where it is now, rotate it back half that distance and you would be very close to TDC as well.
Anywhere close to TDC and both exhaust and intake valves are always closed and you are okay to check clearances.
I always bring each cylinder to TDC using the intake valve open/close sequence and then piston to top and adjust that cylinder's valve.
The attached instructions allow other valves to be adjusted. I'm old school.
More work but never wrong.
Good Luck.