who has a shaved firewall?

[one low c10]

I am thinking about shaving the firewall on my 84, it is only gonna be a fair weather truck... so my question is do you guys have any problems with running no heater? I am worried about fogging windows and what not. I know there is stuff you can put on the windshield to keep it from fogging up but not sure how well it works. the truck was an ac truck originally and everything is long gone. I just want to clean up all the holes in the firewall. could I shave the firewall and leave only just the blower motor? sorry for all the questions and long post! thanks for any help!