I'm bowfishing with one of my longbows this year and it currently has a leather rest with calf-skin plate.

Its a standard D style longbow with no tapping so I'm using an AMS gadget adapter with standard reel. No plungers or anything like that. I'm using a Muzzy fibreglass arrow.

I do not want to use an elevated rest of any kind.

Will this material hold up pretty good once wet or should I give something else a try?

Nope,  Mud and water will eat it up quick.  Go get velcro. Use the soft looped side and put that on the shelf.  Should last you a full season.

The soft side of velcro is what I use, too.  I shoot a lot of fish each year and I am still on the same piece I put on two years ago.  I have a whole roll of the stuff...should last me forever.

I use the stiff side of velcro for my rests whether target, hunting or bowfishing.

The heavy felt furniture pads you can get at Lowes works really well for bowfishing.I use them all the time,hold up really well.

I have a regular Bear Hair rest on my Grizzly and it works and has held up great.

I switched it to velcro. I'll let you know how it works for me. The arrow seems to slide real good from it.

I ditched velcro awhile back because things hang up in it sometimes. I prefer leather on the rest and calf hair on the strike plate.

I just would use whats on it, i have the original bear style rest with a leather strike plate. It's been through two seasons and shows no sign of giving up the ghost yet.