Masking and painting after decaling

Yes...

As jbrady says, seal the decals, let the clear coat cure, then use very low tack tape. I use Tamiya tape as well, but I stick it against my palm or the inside of my forearm several times to lessen the adhesion. Picks up way less fuzz that way than sticking against clothing.

I've done it quite a bit. Two coats of your favorite gloss to seal the decals. Let that cure and then use a very low tack tape. I use tamiya tape after applying it to my jeans two or three times. You could also try Parafilm M and a sharp blade to cut the pattern.

I have occasionally done it, after use of a clear overcoat. I prefer not to do it, but in an emergency it can be done (but using great care and a low-tack masking tape).  I really avoid it on dullcoated areas- I find dullcoat  to be a bit less forgiving than glosscoat.

Hogan,

I truth, I really prefer to stay away from placing decals and then doing any masking...it's just SO easy to lift them off the model when you pull up the masks.

You might try things like Post-It notes, trimmed to whatever shape you need.  They're really low-tack...a must for this kind of work.  I've had some very good results using Post-It notes...and a lot of disasters using anything else.

I've also seen people use dampened newspaper as a mask...no adhesive...the water tension makes the paper cling to the surface...but I'm not sure about getting a hard edge when painting using this method.  It works really well for Alclad, though.

Good luck!