What kind of RPM's do you get? What about MPG?

For a gasser and a moderate size trailer I would say your numbers are about right.

Biggest factor in towing is wind resistance AKA drag. The faster you go the higher the resistance the less gas mileage. I drive at 65 MPH normallly and I have a 2500HD GMC and tow a 10K travel trailer and my normal flat ground rpm is 2200ish. Uphill grades I jump to 3700 and can hit 4800 depending on steepness and dealing with momentum stealers in traffic in which I've hit 5500 at times to make up for the loss of momentum. Normal MPG is 9.5 towing.

I take secondary roads mostly when I can and because of the lower speed and less drag and in spite of the stop and go I get 10 to 11 MPG. We prefer the slower pace and going through the small towns and making stops when we want over the Nascar drivers on the expressways and waiting for rest areas.

Towing, 4.10 gears, 2100 rpm's, 70 mph net 9 mpg. Same thing not towing bit higher mpg's. 55-65 mph and I see mid teens. On ave tho running around town and all, I pretty much ave 11-14.

IdaD wrote:
This question is so open ended it's meaningless.

Like asking what is the best time and temp to cook meat.
Idk. Brisket is 225 and 18 hours. Ribeye 500 and 8-10min.
Cook one the other way and it’s raw. Cook the other the first way and it’s a briquet when done.

I tow in OD at 1900rpms and get 14.68MPG hand calculated over a 6,300 mile tripm

IdaD wrote:
This question is so open ended it's meaningless.

Just asked what you get. You don't keep track?

The Old Man cruises nicely at 2700 and 8 mpg.

I have a 05 E350 van with the 6.0 diesel (yes, it's been de-Forded) and I tow a 35 Ft. Travel trailer all over the country. I typically get around 13 mpg and hit around 1500 rpm on the flat and 2300 to 2800 going up hills(the higher end in the mountains).

Assuming typical 1/2ton truck towing a 23-30ft TT...7.5 MPG is pretty poor. I would expect 9-10 MPG...but lots of factors. The biggest is how you drive.

If you get into small V6 SUVs or bit diesel duallies...it can change a lot.

This question is so open ended it's meaningless.