2019 ram 3500 dually hauling over 30k gross, just replaced front pads at 130,000 for the first time. Rear still have over half.
$200 pads and if I went to a shop to have it installed would have cost me around 70-80 bucks labor.
If you want to draw from my limited (8 month) experience, I won't leave my house for under $700/day local, or $1000/day OTR. Once I book a load OTR, away from the house, I start looking immediately for what loads I can take to book that $1000/day to get home. Sometimes it's not far, PHX to L.A., NorCal, Denver, etc. But, I ran hard for the first few months to get experience and soon toned it back to higher value, lower volume. It will depend on your local area, your base, your needs as well as your costs. These figures work for me, but I try hard not to leave money on the table.
I can often clear that kind of money per day after fuel delivering RV's with my little truck with no trailer/insurance/operating authority to pay for.
At say 9 mpg you're burning roughly 25 gallons of fuel to get the load delivered 225 miles away, so approximately $75 at $3/gallon. Basically a load that pays $425 to the truck if you're paying the fuel or in other words about $1.89/mi which is a pretty cheap rate in it's own right. Some single-pull campers pay that per mile right now TBH. Now if they could set you up with a dedicated back haul where you're running loaded both ways, that would be pretty easy money, but it sounds like they're expecting you to run empty all the way back if I'm reading right which is crappola. You cant afford to do that running a whole rig with your own numbers unless they're paying you like double that. Us RV guys barely get away with doing that even with cheap overhead.