is running a flow boy worth it?

There are no fees invoilved with crossing the state line, though you will have to set up to cover fuel taxes in any state you run in and will have to file them. You will also have to have the ppropriate registration and insurance to run both states.

A flowboy is an expensive type of trailer, with heavier than usual maintenance costs to operate, and the weight of the trailer cuts down on the payload you can haul. I don't know the rules in Tx and Ok, whether you can hang extra axles under there and pick up some capacity. if you can, then you may be able to overcome the extra weight of the trailer. Biggest advantage to a flowboy is that unlike a dump trailer, they don't have the tendency to roll over, and yoo won;t lift one into a powerline, but that level of safety comes at a high weight, complexity and maintenance cost.

I donp;t know your operating costs, but just as a general rule, the 75 per hour number seem to me to be on the low side. You'll have to figure up the cost of the equipment, the fuel costs, and how much of the time is spent rolling vice sitting still to see if it pencils out. Our costs and incomes here in Michigan won;t match up to what you have because most flowboys here run 8 axles under the trailer and carry a much higher gross weight per load, resulting in higher productivity.