I've only used cable ties for now but I may keep them in place as the grill is very secure on the rungs. The tube clips are riveted on and protective tape would be a good idea. My aka are the original dud e-coating and I'm not fussed about scratches. In fact I think there is less corrosion where the e-coating has peeled off
You may want to hold off on the ladder haka. One of my workmates has just brought in an off-cut of some wall panelling. It is 40mm polystyrene foam sandwiched with coated aluminium. It is very light and strong. It spans 1200 OK (the sheet wasn't big enough to check the AI's 1500 or TI's 1400 span) and a couple of off cut planks (edged with aluminium) may work better.
I'm not sure what it is called- it may be a Stratco product but Ausiports did the extension so I'll try to get some more details when they re-open.
A big advantage with this is it looks better than the ladder and it will probably float!
There are also a number of other options that may work such as aluminium painters planks and aluminium slats over the ladder rungs. I sourced some 50 x11x1.2mm slats OK but only in a mill finish. It was going to cost $400 to get 4 x6.5m lengths anodised though so I dropped that idea.
As you say 'so many questions so much time'
One thing is for sure though -the haka make an already versatile craft that much more versatile. I'm very excited at their potential. I was a big fan of the tramps when they came out but the haka concept does take it to another level.