Okay, i'm going to try to help you.
Yes, the host can get out of the map as well, but it's harder as mentioned above.
Best way to guarantee it to work 30% of the time is to Use Net Tools 5 right before the zombie pulls your board and have the other player or players use their Net Tools 5 to lag you as well. You can use just your Start Triangle method if your on PS3 but Net Tools is way better.
Problem is you MUST Know how long you can lag, by knowing how good your own internet connection is and knowing how many times to put Data in the UPD Flooder. Once you figure out the "best" amount of Data to input then try your luck.
My connection is not the greatest, enough to play without lag. So i found the best amount of Data to input and i just turn my on and off quickly while i'm standing on the board so that it does not disconnect the players in my party. Remember, if your host, and they are lagging due to bad connection or their own lagswitch, it lags the host which in turn lags the players. It's a good loop