The Tuesday Burn...

Got a question about how many calories I'm burning, but it requires some explanation.

in my diet profile on MFP, I list my activity level as "Lightly Active: Spend a good part of the day on your feet (e.g. teacher, salesman)" because, well, I work retail, 36 hours a week, on my feet moving around for 90-95% of my work day.

Because I list my daily activity level as above, I don't count my work day as "exercise."

HOWEVER, every Tuesday, my work day is much more strenuous than the rest of the week, and I feel it should count as exercise, but I don't know how I'd go about calculating how many more calories I'm burning on Tuesdays than I do on an average day. That's where I need help.

I work at a pet store, and my average day consists of walking around the store, helping customers, straightening shelves, cashiering, maybe some light cleaning. Nothing too rough.

On Tuesdays, we get our weekly shipment, and my job is to stock dog and cat food. So, for 7.5 - 8 hours, I'm lifting loads between 20-40 lbs, carrying them, crouching and putting them on shelves, continuously, for the entire shift. I sweat my butt off and am beat by the end of the day, so I figure I should count this as exercise, right?

Can anybody hazard a guess as to how much I might be burning on these days? Any insight is helpful. Thanks!

Also, as an extra push, I did this shift today with 5lb ankle weights on the entire shift. How much more would that be?