Dumb idea or workable?
Thinking about adding a couple to my chameleon mpls antenna kit

I have read of people using measuring tapes to make dipole from so should work.

I don't see why not, as long as all connections are clean and secure.
Heavy open die forging, heat treating, and machining plant that I retired from as a Master E-Tech was I.S.O. 9001 complaint.
Everything had to be calibrated, even tape measures, made a lot of paper work for me, with furnace and equipment calibration, every  N.I.S.T. certified test instrument had tested against another, making a 5 minute procedure take an hour, due to warm up and such.
Easy money for me!

After one year tape measures were replaced and taken out of service and tossed in a box, even if they were never used.
Free for the taking as they no longer had a unique cert. # on tag, was removed.
Most were like new, I have a bunch, great idea for portable ops.

I'd fo.

I've also seen guys use drop cords....

I kinda liking the idea of easy deployment and break down...plus the added bonus of being marked for varying frequencies

Use those those clothes line reels like they do with the Yo-Yo Tenna link to pic
73,
Rob

For a 2M HT counterpoise, one of those retractable steel cord reels for badges/keys, which should unspool more than 19 inches to be safe.

I made an entire 1/4 wave ground plane antenna for 2m use out of nothing but a connector and sections of steel tape measure.

Note that steel doesn't work the same as copper, and your element lengths will not match standard calculations.

If you're talking about a variable length counterpoise, you'll have to test to find the right lengths for your frequencies, but your idea will work.

I bought HF $1 tape measures. Attached alligator clips to the ends with wire and made 4 x 20m  or less elevated ground plane radials with them to go with a Wolf River coil setup for portable. It works well.

Making them for 40m or longer requires much more expensive tape measures to get the lengths and I was not willing to do that.  

After a while some of the cheap HF tape measures no longer lock at length  which makes them unusable

You could drill a small hole in each end of the tape and use a piece of a steel coat hanger or similar to secure the ends to the ground.

at $1 each I just bought new ones and threw the ones that would no longer lock out.  I use them in a 1 foot raised position with PVC pipe. 4 tuned 1 foot or higher radials works as well as 32 in ground radials.