Ok, I found a solution. Instead an otoco trade, I needed an oto one
response = requests.post(f"{base_url}/sapi/v1/margin/order/oto", headers=headers, params=params)
where there is no need to provide a stop loss. So the params would look like this:
params = {
"symbol": "BTCUSDT",
"isIsolated": "FALSE",
"sideEffectType": "MARGIN_BUY",
"workingType": "LIMIT",
"workingSide": "BUY",
"workingPrice": 80000,
"workingQuantity": 0.0002,
"workingTimeInForce": "GTC",
"pendingType": "LIMIT",
"pendingSide": "SELL",
"pendingQuantity": 0.0002,
"pendingPrice": 110000,
"pendingimeInForce": "GTC",
'timestamp': int(time.time() * 1000),
}
This allows a limit-type as a follow-up order.