I'm not a Supertigre expert (I have a couple but am not a huge fan of them) so maybe someone who is can chime in and assist you with the tuning / setup of the motor.

A 3 blade prop will help you IF you can get the motor running slow enough to use the prop disc as a brake, otherwise the difference will be minimal.

It sounds like your real issue is a ground run one. Have you thought about using some fuel tubing to cause some friction on the wheels (pseudo brakes)? 300 ft should be more than enough for you to take off with the fuel tubing there.

Alternatively, have you tried running the plane into a tree to slow it down