ALTER EGO STORM

You could Seam seal it no promblem and the zipper is waterproof as for the fabric I have been in peroids of heavy rain for over an hour and it didn't wet out at all. The fabric is very breathable and highly wate resistant. I made the jacket to replace driducks because it is more durable and lighter. Yes it's a niche market but alter ego is a niche company

shower …

id suggest shower test or sprinkler … set it on a reasonable setting … cover up the holes … and leave it on for hours .. put something that shows water absorption inside …

if it can survive a low set shower for hours … itll like survive rain initially anyways

another concern is will the fabric degrade after prolonged rain or DWR (is there such on tyvek) wear off

A tyvek poncho would be a nice addition. Something like 60"x104" so it can have the extra length on the rear to cover a pack. A little velcro on the sides, some tie-outs, and you're in business.

I originally wanted a tyvek poncho, but my experience last weekend taught me that I'd still want sleeves. What about tyvek half sleeves to come with that poncho? Not attached to the poncho though since that would make it difficult to put on.

Eugene heres an idea for "arm chaps." Basically make two sleaves of whatever material you prefer connected across the top with a strip of fabric just big enough for a head hole. Hope that makes sense, sort like chopping off the very top of a raincoat.
I guess you coulde also just make "arm gaiters" which would more or less be tubes of waterproof material attached to your lower arms with rub bands or elastic cord.

Luke, good idea. In my case with the poncho I already have, I think the latter option would work fine. All I know is that my forearms got bitterly cold and quite numb last weekend while hiking all day in the freezing rain.

I'd definitely be interested in on of these, but i would have no use for the pants. Will you offer just the jacket?

Here’s your competition

here

You just made my day Daryl hahaha