if you were going to have a rig for only t-rigged plastics, using around fallen trees and grass beds, what kind of line and lb test would you use?

20# or 30# Suffix Braid. Light enough to let the worm move freely yet strong enough for some heavy cover.

if you were going to have a rig for only t-rigged plastics, using around fallen trees and grass beds, what kind of line and lb test would you use?

The same line I pretty much use for everything and for the past 2 decades: Trilene Big Game, 12 lbs test for that case.

Trilene 100% Flourocarbon 15 lb. test

OR

PLine CXX 12 lb. test clear or fluorescent

I always have a T-Rig ready to go tied with 20lb BPS XPS fluoroarbon!

PLine CXX 12 lb. test clear or fluorescent

X2

P-line is pretty much my line of choice.  12 lb cxx is small enough for good casting but will straighten light wire hooks.  For t-rigs I would also suggest 12lb cx or flouro-clear.  

30# Stren Sonic Braid maybe with a flouro leader depending on clarity.

My dedicated rig for weighted soft plastics is spooled with

#15 Yo-Zuri Hybrid. My jig rig is, too. All other baitcasters

are strung with #12 Hybrid or Hybrid Ultra Soft. For spinning

tackle I use both #4 and #6.

8-)  

65# braid or 12# P-Line CXX.  Depends on the substrate.  I'll sometimes run a leader with braid, but usually that's because the "other" reel isn't in the boat.

My dedicated t-tig rod has #14 or #17 XT on it (95% of the time) depending on the lake.

Since your question involves fallen timber and grass beds, a minimum of 30# braid or 20# mono ( nylon or fluorocarbon ) would be my suggestion. A lesser pound test rated CXX is OK too since it is way underrated for it's actual breaking strength.

30# powerpro

Berkley Big Game 15# Mean Green  

15# P-Line CX

I don't think only one is possible. Some days you will be able to catch fish off the edges, thats when I would go with 15 pound Trilene 100%. Some days they will be in the thick nasty stuff and you will need 50 pound Power Pro.

For all purpose casting to the cover I would go with 15# Trilene 100% Fluro.  Hand to hand combat, flipping in the junk- 20# big game or 50-65 lb braid.

I typically use lighter jigs (Booyah Baby Boo) and I prefer to throw them on 10 or 12lb 100% Berkley fluoro.