Deer will certainly cross them but most of the rules I have seen dont allow you to shoot them from the boat.
This will be my 43 year hunting big river bottoms so yes it is near and dear to my heart. There nearly countless tactics that can be used but I am going to boil it down to 2 primary ways. Focus on food or focus on terrain. To start with food, you need a good understanding of the various mast crops, an order of preference and an order or drop. Then it is a matter of lots of boots on the ground to find as many possible sources as you can and hang when you find the smoking hot ones. It helps to also understand the types of locations where different mast trees will be located in river bottom habitat. For example, primarily persimmon are going to be in wetter type areas as will overcup oaks if you have them, white oaks will be on a little higher ground, etc.
Then you have terrain. Lots of folks look at big river bottoms as flat featureless places because they are accustomed to hills or mountains. River bottoms will have terrain too though. Sometimes that may be a "ridge" that is only a few feet higher than the surrounding ground or it may be a negative feature like a slough, ditch, lake or other drainage. Sometimes these features will be bordered by thickets and that is a good thing. Sometimes you may have or be able to find areas where storms knocked a few trees down or even better tornado tracks and those areas will create edges and thickets. Then there are the less obvious edges that are formed by big patches of honeysuckle or dewberries or other types of plant communities changes. Some of that you can find e-scouting but a lot of it will come from boots on the ground as well. The tactics here though are very similar to hunting mountains. From a deer's perspective there's not much difference between the head of a slough and the head of a draw, they are going to walk there.
@MSbowhunter48 I would like to talk about your point of thermals pulling towards the water. I agree that certainly can happen but I think there is a big difference between why thermals may pull towards water in the bottoms as opposed to in the mountains. In the mountains, it pulls to the water because the water is lower and generally cooler, both aspects that are going to influence air movement. In the big river bottoms that is seldom the case. There are certainly times when the water may be cooler or warmer than the ambient temp and that can influence the air movement in the bottoms. But I think the bigger issue at play is the thermals following the sun rather than the water. With our big rivers there is a big opening in the canopy which has the opportunity to create a thermal dynamic but the same can be true for a cutover. Early and late in the day in low or no wind conditions the thermals always seem to pull towards the sun or big canopy openings between where you are and the sun. One area I hunt is big river bottoms and roughly 6k acres that virtually all has been cut to varying degrees and over several years so it is a hodge podge of pockets of full canopy, broken canopy and open canopy. The air movements there are impossible to predict if the wind is under 8-10mph. In a half day sit it will usually hit every point on a compass. The only thing I can put my finger on there is the variance in canopy both in created temp variance and obstruction variance makes it an air blender. But even with that on those low wind or calm sits the predominant thermal will be towards the sun.