Hello LaLaMan,Good Luck on your new business.I can't tell you what NJ area is paying for dump trucks.I went into business for myself in 1996,after being a company driver.Starting up is very stressfull,and there's alot of hidden things that will come up unexpectedly.The first couple of years was the hardest.
You've a BIG advantage since you've already steady work lined up in advance.That takes the longest,and it is usually by done by having to work harder than everyone else just to have people notice of you,and give you a chance.
1800 hrs. seems very busy too me for a dump truck in a year.It's possible but I'd use a lower figure,and if it turned out that way you'll be that much more ahead.
Hiring a driver is also a BIG headache,although it must be done sometimes.I think that part of it is going to be the hardest part of your whole plan.Unless you've already someone lined up,that you know you can count on.I hope it's not a relative or a close friend though,because often you'll end up having a falling out at some point during the business.Believe me,no other person is going to care about your business like you,and they will THINK your making millions off them without giving them their piece of the cake.Hire VERY carefully.
It's hard to give a thumbs up,or down with the info that you've supllied so far.The price of the truck,how long you finance it,health insurance cost(for your driver),workers comp.,and the age of your truck,will all affect the final numbers alot.
As for pay,you can write your contract up any way you like.By the load,by the hour,or by the mile.Sometimes a combination is best(hours,and miles)some are written by weight carried.As long as your adaquately compensated,any way works.It depends on what your job consist of,as to which way would be best for you.
I'll assume your getting a new,or newer truck,and average 30mph,for 1440 hrs per year,and charge by the hour.(just for a starting point)Here would be a very rough guess:
Truck price of $90,000.00 @ 7% for 60months=approx. $15.00/hr worked.
Maintanance @ $0.07/mile=$2.10/hr worked
Fuel @$2.45/gal @ 5.5mpg=$13.36/hr worked
truck ins. @$6000.00/yr =$4.17/hr worked
License and permits @$2000.00/yr=$1.39/hr worked
Total truck expenses =$36.02/hr.
If the driver was a sub-contractor,and he was paid via a 1099,at $30.00/hr for the hours worked,you'de still have to factor in extra time that couldn't be billed to the truck.I'll guess 10%,so that brings his portion to $33.00/hr
I won't even try to guess if he was an actual employee.Workers comp.and health ins. premiums will add an incredible amount to his pay.(plus vacation,sick days,overtime,on and on)
So if your driver was a contractor,you'de already be at $69.02/hr just to break even.There's also tax considerations,depending on how you structure your business,and always other cost that are hard to know,without more info on your particular situation.If the truck was older,the cost per hour for paying that off and it's insurance would go down,but maintanance will increase.You may get better fuel mileage,or possibly your plate will be cheaper.Your driver might have a crappy driving record,then your insurance goes up.There's alot of variables.
It sounded like you've thought much of it out already,just try and take into account evrything you KNOW the price of,and when you have to guess,be conservative.Never use "best case scenario"for any of your calculations.
Also think of things that can change,and try to account for them in your prices,i.e. fuel surcharge,pay for time sitting when caused by the person your doing work for if it's not charged by the hour(their loaders broke down,etc.)
Also,make sure you'll have some savings for after you've got the business rolling.If your truck blows an engine,or your driver abuses the truck(they ALWAYS do,when it's not theirs)and it needs more shop time for repairs,it can use up all your money before you even get any coming in.A truck will be "down" alot more than you'de expect.
Unfortunately it's always a gamble when you starting out,you'll never be able to predict everything that you'll have to face.Good Luck!