if you have space & your hanging the frame near a wall, put a small cup hook in level with the mid line of the wheels & run a length of thin rope, shoelace, bale twine or similar from the wheel to the cup hook taking the weight of te frame pulling back in it, to stop the frame swaying front to back as your tightening bolts etc. if your in a shed & can have one either end then thats even better as you can switch your retainer to the end your not working on.
I started doing this with a tube over the joist & dropped the saddle through the loops but i've found a garage storage hook (red plastic covered things that come in packs of 12 from pound shops etc.) into a lump of wood & put across the loft hatch opening is better as you can run the tube through the frame to keep things steadier & also turn the hook 90 degrees at a time to change the orientation of the bike in relation to your tool bench.
I can see the mid-range Park one I use in the shop is now discontinued.....
Been using it as a stop-gap until I had spare cash for a better one but it's been pretty good so far. I've worked on a few very heavy electric bikes on it with no problems.