[JRTJH]

The 250RBS (I believe) is a travel trailer with a rear bathroom. I've only seen travel trailers with toilets that sit "directly above" the entry hole in the black tank. Only on Fifth Wheels with "elevated bathrooms" is there any "angled entry plumbing" to get waste to the black tank.

I'm confident that your toilet sits directly over the black tank "hole". You can turn off your water pump (city water) and flush the toilet (open the valve) and with a flash light, look directly into the black tank. It sits less than a few inches below the toilet.