Many recent septic tanks have an inspection clean-out on the inlet T. My tank is located in the front flower bed about 20' from the end of the driveway at the garage. I just unscrew the cap and put my Sewer Solution end fitting right in. The slope is effectively level between the RV dump outlet and the clean-out, but the Sewer Solution gizmo has no issues pushing everything into the septic tank.
I don't dump via this method every time, but do so usually at least 6-10 times a year. The septic is 14 years old, dating to when the house was built, and zero issues.