This is what I have in my Futaba 9-C. It may not apply to the spectrum radio's, but may give you a better idea (picture) as to how to do this.
#1 mix.....elevons. Both elevator halves move together with the stick back (up), and move opposite when aileron is applied, i/e left aileron, left aileron should come up, right down, etc. Elevons on all the time.
Mix #2rudder to flap, Rudder-Master-100%, Flapslave-100%, rudder channel for top rudder surface, flap (ch 6 or 7,whichever your radio calls for) for bottom rudder surface. On, all the time.
Mix #3-Aileron to Flap, Aileron-Master100%, Flap-Slave-100%again, aileron on whichever channel your radio specifies, flap on ch 6 or 7, again whichever your radio specifies. Assign this mix to a switch, say switch B, for the sake of argument.
Mix #4-Aileron to Rudder, Aileron-Master, 100 %, RudderSlave-100%, again, assign this to switch, B, for the sake of argument.
When all mixes activated with switch "B", all four surfaces will move the same direction with aileron input.
With switch "B" turned off, then the elevon mix works only on the elevators, ailerons, (up, down, left, and right), and the rudder to flap mix will move both rudder surfaces the same direction with rudder input (left and right).
Don;t know if this will help, or just confuse you more, as we have different radio systems, but I too, had to sit and think about this to get my head around it. Then, had to sit and move everything around to make sure all was working in the correct direction. Had to move some of the mixes to -100% to get the correct direction. Just reversing the servos did not do it, I had to go in to the mixes and reverse the percentages.
I tried the hovering thing in the yard, but just too windy, and with all 4 mixes activated, bit too much to catch up to. (thank heavens for the snow bank!)
Will try it without the mixes first, think I will be a bit more successful .
Now, just have to take it out this weekend (indoors)
and see what happens! Yikes!!!