I'm B1.1/B2/C with multiple group 1 types (Cessna and Embraer). I'd like at some point to add Cessna Caravan (a Group 2a aircraft).

From GM 66.A.45
In Group 1 it's always "Type training: Theory + Examination and Practical + Assessment (+OJT on first type in subcategory).
In Group 2 it's "type training + OJT" or "type examination + practical experience".

Now, Cessna Caravan is still a turbine aircraft so does this mean I don't need OJT as I already have B1.1 subcategory types?
If I attended an approved theory training course (Cessna TRU/Glennair/etc.) and took the Part-147 type exams B1.1 and B2 would that be sufficient?
It's almost impossible to schedule theory and practical courses for B1.1 and B2 at these places and I don't want to waste time on courses I don't need.

I'd like to be able to eventually get the full subgroup (2a) and understand that Group 1 aircraft may be used alongside Group 2 aircraft for this purpose (AMC 66.A.45(e)). Has anyone ever tried this approach?