Get yourself a Dritz hem marker. It stands on the floor and has a ball you squeeze to mark the hem with chalk. Or if you have another widow friend maybe you can swap tasks with her. She can pin your hems and you can do something for her.

I usually use a skirt(well, pants, cuz I don't wear skirts anymore)that is similar in style with a hem length I like and lay it on top of the longer one, marking the hem/foldline with a chalk pencil. I leave a generous hem allowance, try it on and see how it looks before making any adjustments and hemming. I do have a spouse, but he has low vision, so can't help me in the sewing department.

Oilpainter- followed your advice and got that chalk hemmer. I gulped a few times because it was a lot more expensive than I thought it would be. Filled it, puffed with my skirt on,---and can't find the markings. I was careful to stand close. The skirt is light grey, but not that light that you couldn't se the white marks. Am I missing something here? HELP.- Barb

I never could get this gadget to work right for me. I could see the mark but I could never get the hem straight. Personally, I think posture has a lot to do with it and it's hard to concentrate on your posture when you're also trying to mark the hem. Don't they have a darker chalk to use? Check that out and see if it works. (I assume it is chalk. I haven't tried it in many, many years so don't really know)

This is what works for me. When I put my skirt together, I make sure the pieces are even at the bottom and sew the seams bottom to top. If the pattern is way longer than I want I shorten on the pattern line for altering the length. If it is ok, I measure the hem and pin it in. If it's too late for this and your bottom hem is even measure up to your cutting/hem length and mark that line and cut or hem. Unless you're extremely sway backed, this should work for you. I had a good friend who had this problem and all her hems had to be modified to be shorter in back than front to make them look even.

Personally, I have never had anyone around to mark a hem for me. Even when I was married and had kids at home.

I've had this same problem. Even if I make sure all the pieces are the same length as I'm cutting/sewing, that doesn't mean the hem will be parallel to the floor when I'm wearing the garment. The bumps and lumps of my body are not necessarily equal on the front, back and sides.
I, too, bought this hem marker you are talking about but haven't tried it yet. I thought chalk in other colors was available for it but maybe not?
The other thing I thought about trying is to get one of those chalk line markers that carpenters use. You can pick them up at the hardware store. (Come to think of it, you can get loose chalk in red and blue for them. Maybe this would work in the hem marker too?) Anyway, I thought if you measured carefully, say 24" (or whatever height)from the floor up on both sides of a doorway, put a nail, screw or tack in, and tied the chalk line thread around both sides, stretching it taut, then stood close beside it with the skirt on and slowly turned around, allowing the skirt to brush against the chalk line, that would make marks on the skirt at a consistent height. Then you could take the skirt off, connect the marks with a fabric marker, and use that as your hemline or as a line to measure up or down from if you wanted it longer or shorter. You'd have to be careful not to raise or lower yourself as you turn though. Maybe step away from the chalk line, turn 1/4 turn, then step back to mark?
Of course, the easiest method is to find another human being. Maybe a staff person at your fabric store would help?

If you do a lot of sewing for yourself, the obvious solution would be to shop around on ebay, craigslist or etsy (to hame a few) and get a dressmakers dummy. They're adjustable to your size and height and you can mark the hem yourself. If you can find one for a reasonable price it might be worth it even if you don't do a lot of sewing. My neighbor even has one that she can adjust for her round shoulders, sway back and tummy bump.