When I double ramp, I'm always ready to add layers of protection based on where my enemy last was. If they can drop then I'll place a wall/floor behind me or if they spam then I'll add a wall and a roof above me.

In my experience, a lot of people jump into the first ramp so they can place a wall behind them as soon as possible. You can also use the protected double 90 which starts with 3 walls instead (the extra wall being behind you). The prior may not be applicable and the latter may be insufficient.

My suggestion is to place the floor between double ramps if you know the enemy may drop. This will protect you from below and connect your top ramp in case it gets shot out.

At a higher level, this can be disadvantageous as it may require a jump or slowdown, however I usually combo this with my top layer protection as well and on a good day I'll lose minimal speed.