Greenhouses are a sickness, once you get one, it won't be big enough.
You'll end up with hundreds if not thousands of starts.
Your outdoor beds will be full.
You will have to take the extras to the Farmer Market.
If they don't sell there. You bring them home and double your garden size.
25 raised beds
Now what do you do with all the extra produce. Back to the Farmer Market.
and if the produce doesn't sell,
Now what? Animals
Ducks and Rabbits
All of this just because you wanted a greenhouse
Don't say I didn't warn you.
All in good fun. Hope you get your greenhouse soon.
Also, Youtube has some videos on Harbor Freight kits and the modifications.