The best way to add those CC fees is to add them as a line item. You can create a processing fee prcpart, something like ZZZProcessingFee, and be sure to set it’s default transcode to charge so that it has no inventory impact.
MiscChargeType is used to inflate the resale on a quote when you are estimating a BOM. You try to get all of your costs, then set a resale from there. The misc charge lets you account for some of the odd costs that come up so you can set a decent resale on the quote line.
We also do things like tariff charges this way because you can set the misc charges to show not as part of the line cost total, but to show up as a separate charge line.