Sounds like you're on the right road. I bought my pans at Family Dollar Store but I didn't see any pans wider than that. After searching I found that what is termed "1/2 size" or maybe "1/2 sheet" cooking trays/pans are all 18"x13" which might come close to what you need. Something you might consider if you can't find trays or pans long and wide enough is to find one that the length would span the narrow dimension of the bottom board. It could be slid all the way forward next to the entrance leaving a few inches at the back of the hive open for ventilation BUT you'd have to figure out how to over-screen the area not covered by the tray with window screen to block beetle entrance through the #8. You would also need a way to seal the gap between the back lip of the tray and the open screen above because there would be no wood there to "seal" the tray against.
An option, though more expensive, would be to order some of the Freeman beetle trap trays in 10-frame size...Kelley's and Rossman I believe both carry them and I'm sure other vendors do. From what I understand they are nice trays...but, I don't think the beetles pay much attention what kind of tray it is while they're doing the oily backstroke. ;)
I'm not sure about what to tell you on stores for the weak colony. I got my first hive of bees last December (yeah, kinda strange time, eh? :)). It was *maybe* three full frames of bees, a touch of honey and pollen with a patch or two of brood. I gave $1 a frame to my mentor's best friend for them so the price was right...they just wanted me to have some bees to tinker with until spring. Anyhow, I wasn't sure about pollen but I kept syrup on them. Knowing they were a small cluster I wrapped the cement blocks with roofing felt to block the December winds off the screened bottom board and to grab a little solar warmth for them during the day. These bees had a heavy dose of Caucasian genes in them so they managed better with a smaller cluster than I believe a big Italian colony would have under the same situation. Anyhow, these bees packed away the syrup. I had some camillia trees that bloomed along that time so they were bringing in the pollen from those trees and from somewhere else. I guess I did too good of a job of building them up with the syrup because they swarmed that spring! :roll: Ah well, I'm learning. ;) So bottom line...I don't know what to tell you about the pollen end of the equation but I would definitely put some syrup on them. 5:3 seems to be a good all-around ratio. Just watch out for them packing the hive and creating a honey/syrup bound situation. One good thing is that you indeed still have your fall flow coming so that will handle a good deal of feeding for you.
As for the feeding pail I use quart mason jars with holes punched in the lid. The lid has to fit against the screen so the screen naturally has to be on top of the inner board or either a hole cut large enough for the jar lid to sit into and the screen on the bottom of the board. I got plenty of mason jars on hand and they seem to work good. Being only a quart you will have to monitor them a little more often than a gallon feeder and you probably won't make up as large a volume of syrup at one time...those aspects can be good or bad depending on your management system. :)
An old beek showed me a trick to get the canning lid surface in closer contact with the screen. Flip the lid over inside the ring so that the gasket is facing the ring rather than the jar. If you look at the lids they are "recessed" inward just a small fraction of an inch...turning them backwards in the ring makes the lid's recessed surface point outward bringing the lid surface closer to the bees. He said that it did not leak doing it this way, either. I tried it once last year and it did not leak...it was towards the end of feeding and I haven't fed since then so I haven't tried it again.
Sounds like your being proactive...keep at it!