I am heading up to the Grand Mesa, and although I will have my kayak, I purchased my first float tube. I read that your feet fins should have a strap, and one time adjustment. But what about the slip ins that float. Also I see that they are sized at (mens 8-10) and such. I will need to wear my thin waders at the mesa, and with socks and thin stocking foot Simms waders, what size do I need for my size 11 feet?...Lawton.

This link will give you some ideas. The size can vary depending upon whether you're wearing boots, wading shoes, thick socks on a later trip, Etc. Take those things that apply with you, when you go to buy your fins. It might be a good idea to try everything out and practice before your trip.

https://www.theflyfishingforum.com/forums/index.php?threads/float-tube-fin-advice.757926/

Omegas for walking, ping pong paddles for a backup.

I use an extra string to tie my fins around my ankle as a back up to losing them if the strap loosens.....and it will

Here's another way of float tube or kayak propulsion, similar to ping pong paddles,

https://armfins.com/

Check out the very last video at about 30 seconds for a very efficient 2 arm rowing method going backwards, I got great control and better speed, compared to paddling forward.

No way was I going to spend that kind of money, I tested the concept out on my float tube with an old cheap plastic kayak paddle separated into two separate arm paddles, one for each arm. Speed was about equivalent to using oars, and much faster than with fins for me, so long as I had my feet on the Float Tube crossbar and out of the water. Of course, the disadvantage is that your hands are not free to operate fishing gear while rowing in this way.