To the best of my knowledge, if there is a loss, there is no way to claim it and also no requirement to claim it.
I went through it a long time ago. I think you are on the right track.
Since you mentioned the ACA:
1. Traditional to Roth conversions create income for purposes of ACA subsidies.
2. If you have an estimated income that is accepted and you get advance premium tax credits, you can still get the ACA subsidies even if your actual income ends up too low as long as you otherwise qualify. From the instructions for Form 8962 (line 6):
"Estimated household income at least 100% of the federal
poverty line. You may qualify for the PTC if your household
income is less than 100% of the federal poverty line and you
meet all of the following requirements.
• You or an individual in your tax family enrolled in a qualified
health plan through a Marketplace.
• The Marketplace estimated at the time of enrollment that your
household income would be at least 100% but not more than
400% of the federal poverty line for your family size for 2019.
• APTC was paid for the coverage for one or more months
during 2019.
• You otherwise qualify as an applicable taxpayer (except for
the federal poverty line percentage)."
(
https://www.irs.gov/pub/irs-pdf/i8962.pdf bottom of page 8, left column)