Put it at 0 and see how fast the big money brokers start bitching. Illegal immigrants are a necessity for our capitalist system, despite your disdain for them. Farm labor, construction, food and bev, etc are all reliant on illegal immigration. Listen to the CATO institute and establish a daily limit and you’ll see benefits.
And before the knuckledraggers come along and say I’m for open borders (I’m not), I’m also not naive enough to think eradicating it completely would be a benefit for our society. There are people much more intelligent than me out there who study this and have probably come up with a formula to determine what the daily influx needs to be for economic balance