One of the major problem in a steel
boat is water sitting on the hull
plating. It pulls off the paint
and then spot corrodes that area.
My solution has been to fill every place where water might collect, and I can't fully drain with limber holes, with generic 5:1 epoxy resin.
It sticks to the steel/existing paint
so water cannot go under it and prevents water from pooling.
My suggestion is a variation of this. Drill the largest possible holes, seal them with your favourite sealer (mine is 5:1 epoxy thinned 15%) and then pour in straight epoxy resin to prevent any pooling.
Use large holes as good airflow is going to be as important as drainage to keep the boat good.
Most limber holes are going to be in non structural areas. If there is any doubt then local reinforcement must be used.
There is an Allied Seawind Owners Website
with a huge amount of information. I did an advanced Google
search of it using limber and found more information than I had time to read.