None of the theory mentioned is specific to a particular type of wing. The question is essentially whether this wing would benefit from some camber for the power-off glide. It seems pretty likely that zero camber is not ideal for this task, and the TWISTwing is configured appropriately for meaningful camber variation (full-span ailerons with long chord). Moreover, the low aspect ratio makes tip stall fairly unlikely.
Decreasing drag could only help, but I wonder whether a folding prop could be found that would be a good choice for the other tasks.
banktoturn
ORIGINAL: dick Hanson
I suspect some of the lift theorymentioned is based on design parameters totally UNLIKE the TWIST
If you can't reduce weight aft CG. n a low drag propis about the only hope
Take a look at the planform- it is a great aerobatic setup -one of my favorites
the aspect ratio is about 4.something to 1
this means the airflow moves heavily toward the tips
I always used a rule of thumb that the "tip" span was equal to the tip chord -on a setup like this
this means the tips are1/2 of the the wing.
In that air follows the path of least rsistance ,
(try and change THAT one) the best bet is lowest possible angle of attack.
this may mean letting the model speed up a bit more than you might think
tha aft cg (the more aft the merrier) increases total lifting area and if you can be gentle on the elev , ithas to help.
going for tip platesis probably a no nofor the contest .
I am no good at theory or math (Ionly have five toes so base ten is out)but )I found that tip plates can work on stubby wing setups -and work very well