I'm not an expert on Tenacity, but I'll give you my anecdote from this spring. I have a 12k sq foot lawn. I mixed 1.5 oz in 6 gallons of water. I have a 4 gallon sprayer. Takes 6 gallons to cover my lawn with a tee jet nozzle on my sprayer. So I did 1 oz in my first tank (4 gallons), and then 0.5 oz in my 2nd tank (2 gallons).

I had great results on my TTTF lawn. I would think you are fine at your proposed rate.

 

11 gallons to do 1.25 acres? I think you need to slow down. Most products will call for 1-2 gallon of carrier per 1000 sq ft.

 

The Tenacity label states 4-8oz in at least 30 gallons of water to cover 1 acre.

The most common carrier rate (water) is 1 gallon per 1,000 sq. ft and you're only using 11 gallons to cover 65,000??

 

11 gallons to do 1.25 acres? I think you need to slow down. Most products will call for 1-2 gallon of carrier per 1000 sq ft.

Yeah, this is even more true of foliar applied products too since you need even coverage. Soil-applied can be diluted less (more concentrate) and applied with less water per k. Always always follow the label though. Some give recommended gallons per k of carrier, some give minimum dilution ratios, etc.
I would def be using more than 11gal for 1.25 acres.

 

It's a tow-behind-the-mower sprayer from tractor supply.

So this is where I came up with the amount, figuring that I'm doing a blanket coat. My yard is figured to be 21,800 sqft.

https://www.grassdaddy.net/tools/tenacity-calculator

 

You're still doing roughly .5 ga carrier rate. Mark out a 5000 sq ft piece of your yard, put 5 gallons of water in the sprayer, and figure out how fast you need to go to cover the area and use all the water. I downloaded a bicycle app on my phone and found that I need to go about 4.2 mph to put out 1 ga of water per 1000 sq ft.

As stated before, some apps take less carrier and some take more.

 

Why are you spraying Tenacity? The spurge power that you have would probably work better on what you are targeting. (clover, ground ivys) it has a Triclopyr ester that might work better during the 10 day cold stretch predicted. I just dont see tenacity being the right tool.

Also you could change your profile to 1/2 acre lawn, if that is what your are spraying for.