According to Google maps there is a Sam's in Covington. I'm located in Victoria, TX and our Sam's has 25# & 50# bags of sugar (most of the time)25lbs bags are now hard to find around here and it only does 4 gallons. So been buying the 10lbs version. Funny cause the sugar cane fields about 70 miles from here. Dominoes sugar a popular one caught fire from a hurricane and guess sugar may be short with the covid19 and everything going on.
To address the hot water issue. Maybe painting a bucket or 30 gal. plastic drum black & setting it out in the sun. Not sure what temp the water would reach in mid-afternoon, but here at my house it would be hotter than I'd care to stick my hand if very long. If drum were elevated a couple of feet off the ground you could have a valve at the bottom of it and drain the hot water into your mixing bucket, etc.Not to mention I'm in the south with 80 to 90 degree temps outside.
Would limit your window of time for mixing and be dependent on the sunshine, but would provide a volume of hot water with limited cost and would allow you to monitor from a hammock while searching eyelids for leaks.