Hi (again) Keepontrickin,
If the twin props are exposed then just use a mixer either one built into the transmiiter (elevon type arrangement for model aircraft) or buy a simple mixer from your model shop which are magic for this sort of application and very cheap and very small. It needs two speed contiollers but gives full manouverability with the model able to turn in its own length.
Concealing the props will make it much harder as you won’t get any reverse thrust from the prop unless it is a straight-through tunnel. I know it well from my own model Amphicar!
Front wheel-steering on a model is fun and will get the model to turn – but only when it is moving at speed – you cannot turn when going slowly! My experience also is that the model wiil eventually respond to the turn but, once the wheels are straightened, it keeps on turning! Only applying opposire stick gets the model back on course and the whole proces of keeping a straighht line is a constant battle with the steering. Eventually I fitted prop and rudder steering in parallel but that required a third speed controller for when I used the land drive motor. All very complex but it works very well on land and water in the end..
Bob