Phil, I actually have something you could experiment with:
I think Pam told me about a "rice warmer", more than a year ago?
I just threw one together for our chihuahund, little shiver dog,
and it is fascinating. it keeps deep heat in it for so long, HOURS beside him in the bed.
strong, thick athletic sock has enough room (Jim's size 12s) for about a pound of uncooked "mainland" rice, the kind that cooks long (not instant).
I tied a knot in the sock and throw it in the microwave, low heat 2 minutes.
to make it last a long time, i wait 5 or 10 minutes and do the heating again, before taking it out at all.
this is too hot to put against the skin, but put it indirectly close to aching feet or legs, or back.
I am thinking about denim or mattress tick, and how shapes and sizes can be easy to keep near a knee or elbow.
problem is, this stuff gets too hot to put ON the body.
GEM, the ulcers are damn scary. We had a close one recently, living a bit primitively and all: if anyone has ever seen the "end game" on this, you get REAL motivated to take control early. So we started soaking feet in hot soapy water ... and wedging a stool in here to elevate the feet.
it is about circulation, low dose aspirin has helped too.
I hope we all can improve our vulnerabilities by swapping tips. God bless and keep you all.