All sounds good. Ambient temps are important. Keep temps in check and you b good. I would make sure of air movement...4 inch is a bit small IMO. Don't overwater and let patience rule.
Oh yes, if temps outside will go over 30C, there will be hot as hell inside.
In that case airflow over bulb is almost a must.
When hot outside, everything will be hotter around bulb, not only air but wood too. Hotter air from outside also means less exchange of temperature with bulb. What works in Alaska is maybe not good for California.
We live in different parts of the world and what you see working on the web is maybe 10000 kms from you in totally different climate. If you grow on large scale than you just invest to overcome this obstacles but in a small place with limited budget small mistakes may be fatal.