Hey, Bish,
No major modification that I know of. There were three metal frames attached to the roof of the bomb bay, one for each clip.
To show the clips installed, you will need to have the bomb bay doors in the load/service position. To do that, you have to cut out the upper section of the bomb bay doors, which is easy to do. In that case, there is plenty of clearance for the clips.
If you choose not to cut out the upper sections, there could be a fit issue since the total width of the clip is 25 mm - exactly the width of the bomb bay. In that case, you might have to trim the bomb bay lip 1/2 to 1 mm on either side. Or, you could leave off the I-Beam trim around the edges and inner slot on each clip panel, which should provide enough clearance. Note that with the doors not in the load position, you can only have the bomb bay doors hanging straight down, which blocks the view of the bombs except from the front or rear.
One thing - there are 28 bombs on each clip. The only MK-82 bombs I could find in quantity were made by Verlinden and there are only 12 in each set that can be used, so it took three sets and that cost almost $40 US. I'm not likely to build two more at that price. If I build a clip or two to hang in the bomb bay, I will only populate the lower row of bombs. That's about all you can see from the outside anyway.
I'm writing an article on how to build the bomb clip and trailer and install them in the model. It's not quite finished yet, but I don't have a website to post it. Do you know if FSM will allow you to post something like that here? I can convert it to an HTML document but I don't have any way to convert it to a PDF document.