Welcome to the party
This is something you'll need to master dealing with, especially if you get into forged blades. Figure out how to make it as painless as you can for yourself now....there will likely be many, many, many more.
Don't use aluminium clamps, they'll probably fail if you heat them under load. The paint will probably be ok, but I'd invest in steel clamps. Doing a shimmed temper should correct the warping, but keep in mind a household oven is not calibrated like a HT oven and may considerably overshoot your target temp. Test it out with a separate BBQ type thermometer to see where your target temp actually is on the dial. I had a toaster oven that overshot its dialed temp by 90 degrees F.
If it doesn't work, try drawing back the spine with a torch and try it again. If that fails, try peen straightening.
I don't know if you pre-ground it, but I quit pre-grinding air hardening steels and deep hardening low alloy steels early on because I was wasting sooo much time straightening blades. It's much more economical to just use the extra belt or 2 and grind from full thickness bar stock after profiling.
Good luck