My personal take is you could proxy but not use counterfeit. The proxy should be obvious. I don't use proxies personally. But i'd want to know you are playing one.
Less cards means more streamlined and more super competitive decks. "Subpar" cards are more than just filler. They represent the surprise factor in edh where your "subpar" cards ended up winning the game or made the game more interesting.
Wort the Raidmother. Play different decks and choose either red or green. If you're green copy stuff like mwonvuli acid moss or plow under. If red copy goblin token stuff.
This. If you run top card of library manipulation it could help. Sylvan Library, Brainstorm, Ponder etc. The potential facing Thalia, Heretic Cathar and its ilk is quite common in CEDH.
Viscera Seer
Phyrexian/Ashnod's/Dementia Altar
Sadistic Hypnotist
Greater Good
Yawgmoth
Phyrexian Tower
High Market
Miren
Cabal Therapist
Unbound Flourishing
Force of Vigor
Good-fortune Unicorn
Sword of Truth and Justice