Making an entity's hitbox able to be attacked through

In one of the mods I'm making, there is a large bubble entity that is spawned, giving a visual representation of the area it affects. I need to keep the hitbox very wide so that it doesn't dissappear when the player looks away from the center, but it blocks anything from being placed on the bottom blocks of it's hitbox. Is there any way to make its hitbox function more like a lingering potion, where the player can place blocks and hit things through the hitbox?