NC Miata drain holes- being a PITA

The short version of this story is that the drain holes in the NC I picked up a while back were clogged. 

Taking apart the interior, as mentioned in that thread, was too large a job at the time. So, what I did was to go underneath the car, open the drain flaps with a pick and run a trombone cleaner through it from the bottom. A bunch of gunk came out, and the holes drained well for a while. Unfortunately, this car resides outside and there are a bunch of mature trees around, so lots of debris is constantly falling on it.

The last storm I got, there was water on the floor boards again. I am unable to get my fat hands in there from top and run the trombone cleaner down very well- I keep missing the drain hole and pushing the cleaner through the interior OR it's so blocked up in there that the cleaner just skips over the top.

I plan on going under the car and cleaning it out again. 

Moving forward, is there a trick to cleaning out the drain holes? Would removing the black plastic covers over the drain holes impede draining- in other words, do those covers guide the water towards the drain holes? If they weren't there, at least I'd be able to get a vacuum in there to get most of the stuff out and SEE the top of the drain hole to get the cleaner in there.

Should I just store the Miata with a tarp over the top? Get a car cover?

Free Thursday bump for you. Anyone been through this before? 

is there any way you could ram one of these HVAC Drain Gun rubber stoppers into the hole and blast it clean with C02?  i haven't been around an NC chassis to know if that might fit or mate up.
https://www.amazon.com/Homiom-Drain-cartridges-Included-Condensate/dp/B071JS76ZP

In reply to Brett_Murphy (Agent of Chaos) :

My  NC sat under a massive and glorious live oak here in FL. So depending on the season the drains would get clogged with pollen, leaves and acorns.

I just got on a quarterly schedule of cleaning the drains. I definitely remember getting better and hitting the drain hold with the cleaning rod, but don't remember removin the black plastic covers. I don't recall using a vaccum, but seem to remember pouring a couple quarts of water down the drains at the end to make sure they were clean. 

tl;dr trying cleaning it quarterly and getting better at hitting the drain hole. The angle of the dangle matters, so to speak.

In reply to CrustyRedXpress :

Thanks! I cleaned it a few months ago, so I am thinking it may be a monthly thing for where I live. 

In reply to ScottyB :

That might work if I could figure out where the dang hole is. I keep watching the videos and they make it look easy. I'm going to have my wife (who has much smaller hands than I do) try it out. I figure it can't hurt.

Maybe this?

$900 Tractor Supply.  Your Miata could be outside and inside at the same time.