Is the pic you posted of the keel band? And where exactly is separation between layers of mat? Can you post better pic? The separation is caused by resin failure which will have been caused by damage to telcos then flex then water. Older resins and mats were nowhere near as good as modern and things like water ingress caused by osmosis in fibres was a problem. The real answer is to cut back until the separation is gone - as it’s the keel (I assume) it’s important to rebuild strength and integrity. You will need new mat if it’s a patch larger than about 2 x 2 in. Cut to size and bond/ fair as best you can using filler. The problem is access because ideally you want that keel band out the way.. keel bands are a total PITA on glass boats - if the boat is trailered right ( ie trailer set up properly) you h wouldn’t need it. Drilling holes into the bottom of a boat for screws is asking for trouble! Make it part of the long term plan to get rid of it. If you have better pics can maybe offer more advice.

Sounds like a plan.

If you do need to flip it at a later date it’s not that hard on a boat this size. Loads of tyres to lift onto first and a second line to protect gunnel as as pivots up. The screen height ( assume it’s pretty standard ) is bout 30 in max?? This is can be managed with tresle height- or even a stack of tyres if you have a pile to access. Three blokes should take care of it. Obv any rocket launcher etc need off first. It always looks a mission but as long as you have manpower it’s not as risky as you think. If you could manage I would strongly advise- you always get a much better result in any proper small boat keel repairs if the whole length can be exposed and accessed easily. If it’s a no go it’s a no go. You can still improve the integrity a lot with boat upright but will need to mix things a bit stiffer to reduce working time and hence any effect of gravity before u get any covering films in place for curing

The 8mm separation will need mat by the time you cut back and building up again to follow profile bearing in mind it will need properly fairing at some stage. You won’t really know how best to attack it until you e got the whole area back to solid glass/ gel coat. Post up some pics at that stage and we can pitch in our 2c if you want it.

On thickening up- you can up the catalyst a bit- no more than 10pc- which can speed up- but easiest way is to mix normally and let it go off until you have a consistency that will not be too deformed / pullled out by gravity. You will end up wasting a bit more and timing is key getting things in place before mix becomes unworkable. It’s all a bit trial and error but start with small amounts and see what works best and build up the layers.