What about a Do335? But dump the front engine, replace it with radar and guns in the nose. Add a second seat - would have to be behind the pilot. Use the best DB603 version available.
Anybody got the performance numbers of the Do335 on a single engine?
Single engine performance of the Do 335A-0 was 348mph, I think this was only with the DB603A engine, the 475 mph DB605E version would have been even faster and the 495mph
DB603L version faster again.
For microwave radars (9cm and 3cm) Dornier was preparing the Do 335 to take dielectric rod radiator aerial array in the leading edges of the wing by making the leading edges of wood.
http://www.cdvandt.org/CIOS-XXXI-8.pdf
The Berlin series of centrimetric radars tended to use arrays of these rod aerials, they are like tube and produce a narrow beam from the tube, when arranged in an array of anything from 2 to 8 or more the beam becomes tight. Came out of the technology developed for the FuG 350 Naxos radar homers and warning devices. The so called Arado Ar 234 "AWACS" used this in a dish above the aircraft.
The Luftwaffe's night fighter needs to be BIG and probably needs 3 crew to handle all the equipment:
1 Active radar plus a tail warning radar. Active radar was being developed to have pulse doppler clutter rejection as on groaund based radars with windlaus.
2 FuBl 3 automatic blind landing instrument
3 3D autopilot
4 Passive Radar such as Naxos
5 FuG 16ZY to give distance and bearing to a becon
7 Bernhard/Bernhardine jam proof navigation becon which also provides general telemetry of the bomber strams position.
8 Large jam secure radio and telemetry system immune to interferenance.
9 Advanced IFF system eg the FuG 226 Neuling system that was replacing the compromised FuG 25a Erstling system.
10 Tail warning radar
11 backup navigation systems
12 Infrared system like Kiel.
13 system to trigger enemy IFF
Really the Luftwaffe needs two types of night fighter: a small fast unit with basic radar to attack recons and pathfinder mossies as well as enemy night fighters and a big heavily equiped version that is somewhat slower but still fast.
Gebhard Adders book on the German night fighter force notes that the Luftwaffe wanted to use telemetry data injected straight into the 3 axis autopilot to guide the interception and then have automatic firing of the guns or R100 or R100BS missiles via radar. A device called Pauke added to a microwave radar.