Are there sewer hookups anywhere on the property? If so, you can often us the sewer cleanout. Either use a tote to take the waste water to it, or if it’s within 200-250′, you may be able to use a macerator pump.
If not, you can use a vessel secured in the truck bed and pump the wastewater into that using a macerator pump. Then drive to the nearest dump station and pay the $5-15 fee for dumping. The vessel can be things like: sewer tote, sewer bladder, 55 gallon drum, or even IBC tote.
Otherwise, contact a honeypot company and talk to them about dropping off a 250+ gallon tank and coming to empty/service it every monthly or so.