Svietlana is really beautifully modded car, there is lot of harmony
I have Vibroblast M1 sound insulation inside of my hood + standard sound insulation, when I added M1 there I did notice that hood is staying frozen even I drive really long trip during winter, seems to be that it adds also some thermal insulation and might be perhaps good for your plans to increase insulation of engine bay?
At least it is easy to apply in summer time as it gets so soft when temperatures are around +20C.