Dealing with frame rot

Hey all, looking for some advice.

I have a small section of frame rot that I am debating how to deal with it. It is about about the size of a business card on both the exterior and lower surfaces on the driver's side just behind the front wheel. (I don't have a picture currently, but I can get one.)

Would it be better to cut out the small section and weld in place a new piece of steel or go with one of those repair caps (1960-1976 Dodge Dart Parts | MM8154 | 1960-76 Mopar A-Body Front Frame Rail Repair Cap (Front Section); LH | Classic Industries

It would certainly be cheaper to go with a small section of steel, and the repair cap seems overkill for the size of the problem spot.

I would appreciate your thoughts, advice, previous experience.

TIA