Trimaran project - Add cross beam + extend cockpit

So

I bought recently a 44ft trimaran and now have plans to make it the way I want her.

First...
I want to add trampoline to the aft part of the boat. I were thinking about adding a cross beam. Either to the amas or to the akas. What would you suggest? Would it be better adding it to the aka due to stress/flexing?

Second...
I would like to make the cockpit bigger. At the moment center cockpit (sort of). In the aft there is an engine compartment that I don't need. I plan to open this up to integrate the new area with current cockpit. The new aft added cockpit shall also be widen with new seat benches extending over the water, connected to the current main hull extension that extends over the water. Shall be around 50-60cm (20-25inches) at the widest part). Suggestions what I should do and not do?