^^ right - you've seen a ton of options & variations, so it's up to you to figure out what will work well for you.
If you go ladder, it doesn't need to be under the filter. If you go airstone, you can use the filter waterfall effect to help delay bubbles reaching the surface.
In any event, HOBs are generally not helpful in terms of keeping CO2 in the water, but they can also help prevent overdoing it... it's all checks and balance w/ DIY. At any rate, having a drop checker may help you sleep better at night, especiall if you get aggressive w/ DIY CO2.