Yeh- basically just preventing a direct , upward heat flow I once worried over all this crap -found out that as long as oil spatter/flow was no problem - just provide some natural path out for the radiated heat from th pipe .
I have seen expensive tubes (look like hamster runs) for "proper direction of air around pipe" - fooey - not worth the time spent ordering them
So far the best setup for controlled temps I have found, is simply to divide the fuselage into two compartments by making a floor which extends from the "firewall" , not the engine mounting plate and back to about end of pipeand then provide a good restraining vertical mount for the end of th pipe . All th radio crap above - and th pipe below
It also effectively stiffens the fuselage

The air exits - a bottom tunnel or slots in the angled bottom between the lower longerons
The lighter the better .
Lafus Maximus?
Do you know -- Biggus Dickus?
His wife's name is Incontinetikus Buttockus