Hello Texan,
I don't have one for rent but you can rent one from a local equipment rental business in about any major city in your area, They usually rent out by the hour or day.
I've been using them for about 18 years, Have owned several types and currently have two of them (TM-800 & TF-900).
They will penetrate low levels of water, Of course we're talking about a couple of inches of water because the detector is actually ground balancing both the ground and water. You just need to ground balance over the area you intend to detect, And reground balance when you exit the bogs, marsh etc.
With experience you can detect small items, Not the smaller size items your normal detector can pickup but with allot of experience a two-box can detect small items. The TF-900 or TM-800 are my two main types of two-box detectors, Others are not the same.
I'll attach a few pics, The two-box is not for everyone and those that buy them usually end up selling them within a year.
Good luck,
Paul (Ca)