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It appears you want to go around a planet significantly faster than at the speed of a normal inertial orbit.  That's gonna cost one way or another.

Something has to create the downward force to keep the craft from escaping into the elliptical orbit (or even hyperbolic escape) indicated by the speed.  Your suggestion is a deliberate burn pointing down.  For a free-flying craft in space, that's probably the only option.

You say you want to stay out of the atmosphere, but what about using the very thin outer edges of the atmosphere to provide downward "lift" with wings?  The dissipation would be the speed times the drag force.  With large enough wings, the resulting heat is more spread out.  The efficiency of the wings also gets better, so there is less drag that causes heat relative to the downward force required to keep the craft in the desired circular trajectory.  The thrust to keep the system going is now only to overcome the drag, which would be significantly less than the vertical force needed previously.

Off the top of my head it seems that the power required gets smaller and smaller as the wings get bigger.  Note that the wings aren't airfoils, just flat things with a slight angle of attack.  The real problems are the engineering tradeoffs to make the wings strong enough, large enough, be able to handle heat, but not too heavy.