This move order, without e4 and Bg7, was employed by Botvinnik in the Tal-Botvinnik 1960 WCC match. If you're interested, check it out here. In his book on the match, Tal recommends going for a quick h6-g5-Nh5 maneuver to win the bishop pair before the kingside knight can be maneuvered to c4, which (in conjunction with the bishop on g3) puts uncomfortable ...
The whole point of hypermodern openings like the Benoni is to encourage a big center. If you don't get that you'd probably be better off playing something else.
The Dutch leads to unbalanced positions, avoids transpositions and can be learned very quickly. The Tarrasch also. Those sound like better choices.
Is the only way to prevent this to have pieces tied down to defending
that square because to me that seems like a waste.
No, it isn't the only way. There are two other better ways:
If you don't like the positions that can arise in a particular opening then don't play it. Play an opening you do like.
Normally in an opening where one side has weaknesses ...
If you don't feel comfortable playing against large centers you shouldn't play Benoni nor other openings such as KID (which both, by the way, are good choices if you look for imbalanced positions).
I would recommend, based on the proximity of the tournament and your aim for imbalaced positions, to look at Von Hennig-Schara Gambit, which doesn't have a lot of ...
In this position, White king is still in the center.
I would go for Re8 (with ideas of Nxe4 followed by f5 in-case he has not yet castled; this in itself is a moral victory for Black, since White's center has been dismantled now)
If White castles immediately, then Nbd7 to add additional defense to e5 square and then look to expand on the queen side.
The thing about the Modern Benoni is that White is usually trying to run you over on the e- and f- files. Black adopted a very small stance in the center (d6), and White's pawn play is the price to pay.
The difference between these two plans for white:
Bb5+, f4, Nf3, with a view toward e4-e5
and the one you describe here Bd3, Ne2-g3 with a view toward f4-f5
This is the crux of the Modern Benoni, right?
Do you know why you're playing the Benoni in the first place? You're trying to post a knight on e5. That's why that square is most critical; White is trying to run over your backwardness at d6 (the reason 6. e4, 7. f4, and 8. Bb5+ is White's most successful), and Black is trying to win the square himself because ...