Apologies for not getting to you sooner!
First, some questions:
  1)  Is the owner CA (Caltrans), LA County, or City of LA?
  2)  Are you aware that you need to use A709 grade 50W if you plan to qualify WPSs for welding weathering steel?  A588 won't qualify A709-50W.  A709-50W will qualify all A709 grades from 50W down thru A36; A572 grades 50 & lower & A992 are included as well -- but not the reverse.  If you'll not be welding weathering steel, don't waste your $$ on A709-50W -- use A709-50.  See 5.4.1 & 5.4.2

Recommendations:
  1)  Ensure you invite the QA organization for the owner to witness your PQR testing.  You'll probably get to rerun all of your tests if you don't.
  2)  Consider running your 1G plate as a min-max PQR (5.12.3.4) to expand your operating range IF you plan to position your weldments to enable welding flat & horizontal as much as possible; when you say 'heavy transportation project' you may have to do most of your welding out of position, so an additional test plate (min heat input) would be an unnecessary expense; if you run a min plate, stay above 18 kJ/inch to prevent a brittle HAZ; your project won't require zone 3 or zone 4 testing, but if it did, use >20 kJ/inch minimum.
  3)  Make sure the welders selected for 3G & 4G can actually run their test plates out of position at max heat input; also ensure you allow their test plates to cool to nearly your selected preheat/interpass temperature; as the plates fill up, they cool very slowly, especially the 4G; people get fatigued & hurried as tests progress; take breaks!
  4)  Use substantial run-on & run-off tabs; consider making your plates closer to 30" long to allow cutting off unwonderful ends
  5)  Prior to tacking, reverse-bend the backing 6 degrees, & 1" plates will be very nearly flat when welding is complete
  6)  Ensure the knife-edge on the plates at their root aren't radiused -- too often they'll fail RT because the roots appear to have lack of fusion
  7)  Run alternate pass directions on the 1G & 4G plates to minimize wedge-shaped fills (under-filled on a start end, over-filled on the stop end -- it's a heat & fatigue phenomenon)
  8)  Watch the welder's torch angle & electrode extension on the 3G plate -- as they approach the top of the plate, they tend to change their torch angle to more of a push & to increase their extension; mount the 3G plate so that the top end is in their comfort zone rather than the middle of the plate.
  9)  Ensure your welding & inspection equipment has been calibrated per 4.28; we won't get into details on this subject because we could go on & on...  Your smart phone will suffice as a stopwatch (for timing travel speed) since it's tied to NIST time
  10)  Maintain bullet-proof (especially in CA ) material marking/traceability -- your QA rep can ask either or both:  "Here's the MTR, show me the metal," or "Here's the metal, show me the MTR."  The material traceability must be verifiable all the way to the lab that slices & dices your plates.

You'll need a preliminary WPS, but this is a chicken-&-egg situation.  Do your calcs ahead of time & determine experimentally what max heat input is optimum for your real-world fabrication -- talk to your welders before you begin (they have real-world capabilities & real-world limitations).

You can do your FWST macros with min & max fills on the same T-joints (one side = max single-pass; other side = min multi-pass), so you'll need only 4 coupons.  Again, have your selected welders rehearse the test so that, optimally, you have a 1-pass fillet equal to or larger than the 2-pass fillet -- not always easy in 3F.

Have your QA rep/source inspector sign your worksheets; recommend making computerized forms.

Again, I apologize for not responding sooner!  Your project is probably erected by now...
gary