I've been thinking the exact same thing... seem a logical step to me.
I was thinking something like the bug nets you use over your bed in the troipcs
only cut shorter with a draw cord in the bottom and holes in the top to thread over ridge line this system would work for both ground and hammock camping.
pull it in tight when hammock camping. would also assit to hold it in place when on the ground under sleeping mat....
Could maybe have a velcro or zip side entrance? pain in the backside to have to stuff a bug net under a mattress every-time you get out.
also it would not have a built in ground sheet which would result in the bugnet wearing on the ground and slipping around if i ground sheet is added.
Anyway i think there is potential for this design if i had the space, tools and knowledge i would have started designing more seriously long ago.
all the best!
PS regarding the above link by "sarge" kinda like it although i would personally hang different tarp height set-ups for ground or hammock camping so would cut out all the excess netting and leave only whats required... Standing up is not imperative plus would keep weight down a whole lot.