Not sure knowing the depth while on plane would be of much use, everything I've ever hit happened so fast it wouldn't have helped. Hopefully the front transducer will work when you are coming into the shore. Maybe have your crew move forward? Now maybe someone will develop a collision avoidance system that has the ability to look forward and to the side like a radar to look for danger? The rear is handy IMHO to keep the drive out of the sand. Looks like your making great progress, that really is a big job to tackle.
This is available from almost any manufacture already. They have both forward and side scanning on them. Most of them you have to have the transducer mounted thru the hull or on the transom so it is physically in the water. Try a google search it is amazing what is out there. A lot of new boats are now joy stick operated. Even the I/O's
Also something to think about. This is right from the Garmin web site.
Potential damage to a transducer when running out of the water
It is not recommended to run a FishFinder and transducer on a boat that is not in the water as you will not get any readings from the transducer.
A normal 500w or less transducer should not have any issues when running out of the water. A higher powered transducer, 1kw or larger, may have the potential of having issues as they normally use water to help cool them down when operating for long periods of time. Without the water, the transducer could burn out and have issues if left running for an extended period of time out of the water.
Last on my 43 ft boat I have a transducer mounted in about the middle of the boat about 15-20 ft in front of the props, at just above idle speed it was still not enough time to react when it suddenly read 2.5ft. The Ins claim was $15,000. All I am saying is if you are using it for avoidance go very slow. You also have to keep in mind how deep the transducer is set below water line at idle and depending on load in the front of the boat to give actual depth. Most systems you can set it to what ever depth you are at so it read accurately.
You're making good progress the 23's have a lot of wood though.