Hi ya,
I made a ONE PIECE (Kinda Cabinet), Twin Walled, & Twin Harthed, Metal heat shield out of sheet Metal Sprayed with High Temperature paint that suited the space & Purpose for what I needed. I even Angled BOTH the heat shielding Tips to encourage the Heat to go Unempeeded Straight Down The Companion way in the center of the vehicle & narrow the ‘Line of site’ heat Path to other obstacles.
May not suit you though,
One of the secrets is AIR FLOW !.
I have ‘NESTY’ That’s my Multi Fuel Stove that nestles nicely between the Drivers & Passenger seats on ‘The Nest’ being my Motorhome & has given OUTSTANDING service & Comfort since fitted & Used as my Primary sorcery of heating for about a year or so now ..
The Stove fire Box is 150x150mm,,,it THEN has its 1st Air Gap of 20mm, It THEN has 25mm of Rockwool Slab Insulation fitted to the 1st Metal Heat shield,,,it THEN has its 2nd Air Gap At 20mm,,,it THEN has it’s 2nd Metal Heat shield,,, it THEN has its Final Air Gap of 80mm,,, BOTH heat Shields have Numerous LOW level ‘Cold Air Draw Holes’ drilled in them to encourage Cooling or rather the Movement of Hot air,,,The Harth is Of ‘Similar’ construction but without the last 80mm heat Air Gap.
The One Piece Flue has 25mm Rockwool Flue Insulation along its entire Hight, With this being Doubled to 50mm from half way up to through the Metal ceiling plate & then on through to the Silicone Roof Cone Extrusion.
Found it hard to show the air gaps properly on the pictures, but hope you get the idea.