What type of structures do you typically use when connecting large storm sewer pipes (i.e. 96" diameter RCP). I'm not sure if they make manholes in that large of a diameter, would you use a Tee with riser?
APWA has details for that and it can be formed and constructed in the field. But maybe better to have it constructed by the pipe company in their yard.
If you just need access (no change in grade, size or alignment) then a tee with risers to the surface works fine.
I have found that prefabrication from the supplier works best. Particularly if multiple sizes, specific elevation changes and/or multiple inlets are to be fabricated. They will ease the inventory process and much easier to manage if there are discrepancies between the shop drawings and the product shipped.