As others have said, there are off-screen buyers and off-screen...

As others have said, there are off-screen buyers and off-screen sellers. So you could set a few sells in the queue each day, multiple times throughout the day

Personally I wouldn't set a massive sell order to avoid spooking the market, so you'll set them reasonably sized (in this case id say probably around 5000 shares at a time).
If you are with a cheap broker like selfwealth, its $10 a trade. 10 sells is only $100 - wouldn't worry about brokerage or high volume of trades


Other strategies include:
- When you see a big buy order in the queue you just sell in to it. Wait for it to potentially happen again, then do it again, etc. You'll obviously need to keep monitoring the market depth throughout the day

- Opening and closing auctions. Usually this is where people can easily offload (or buy) larger amounts of stock

WA1 seems a bit illiquid so i understand what you mean about it being difficult, however, it can easily be done. You'll just need to keep at it daily until you're done