So I've been messing this all day and its kinda broken and hilarious.
Normally when you burrow with the chomper you leave rubble pile, this rubble pile will vanish after a short time if you don't move, but its a telltale sign that you just burrowed, any observant zombie player will pick you off or worse unburrow if they are an engie.
But if you toss a spikeweed down and burrow directly into the spikeweed, you do not leave a rubble trail, you don't leave any trail till you leave the spikeweed, I've been using as a means of escape all day, toss down a spikeweed somewhere then make your approach to chomp someone, if you're getting shot at run back to the spikeweed and burrow into it, provided they don't see you burrow into it, most people will just assume you vanished, then just get behind them and chomp em up, I actually got accused of hacks because of this.
It can also work to lure folks in, most players will jump over spikeweeds if they can, as soon as they just move under them and CHOMP.
Its pretty cool way of escaping/evading people since the chomper while awesome has so many drawbacks.
"Intelligence is not a pre-requisite for existence" "Everybody lies"