Do not, repeat not, use that putty knife. Anything that has notches in it will give you way too much epoxy and way, way too much weight without any benefit to the strength.
Designer recommended AT LEAST 1/4 lb per sq in
That's a total of 125# versus the vacuum bagging system giving you about 7 pounds per square inch or total weight equivalent of 3500 pounds. Which do you think will give you the better bond and stronger wing?
I really want to get this build under my belt before I invest in a vacuum system.
If it's time that's an issue, the ACP system can be there in two days.
No, I don't work for ACP, but after my experience I wouldn't waste my time doing it the way that you are planning, especially since you state
I just don't want this wing to fail on me.
One more thing - Use 1/32" balsa instead of the 1/16" you mentioned. It will give you more than enough strength. It's not the thickness of the balsa that gives strength, it's the completeness of the bond of the foam to the balsa.