Realistically cannabinoids will not readily permeate the skin in MCT or any “carrier oil”. There maybe some localized effects from using this type of topical but to really get your CBD to get under your skin you would need to create a Nano emulsion. This encapsulated form would allow your CBD to pass through the skin and work its way deeper into the problem area it is being applied. I have used both MCT based and nano emulsion topicals and the difference is night and day. I think the more pure your concentrated cannabinoids the better off you’ll be getting them to complete transdermal absorption. When extracting your compounds my personal favorite is super chilled Ethanol. This will allow you to skip winterization that you would have to go through with BHO to crash out undesirables. That being said you would still need to preform some type of distillation process in order to get your CBD more pure.