"another thing that i have done on many of jobs with dual-tuner boxes, is to combine the UHF antenna, and my TV2 signal on the same line to the other room, then in that room split them back apart...
so far it has worked every time
on one job i did... from the back of the receiver, the remote jack, and TV2 out jack into a splitter, then into a diplexer with the sat feeds, then down to the basement through the other diplexer, then out another 125 feet to the metal garage, where i used a splitter, one side to the TV, the other side with the little factory antenna on it.
total it went through about 200 feet of coax, two splitters, two diplexers, and two wall plates... and ended up in a metal building that before the remote didn't work at all unless you had the door open on the side facing the house....
now it works amazing, just as if it was in the same room, there is no delay at all"
( i copied that from a reply from one of the above mentioned threads)
and as far as dumping the UHF remotes, as far as i know, the 522 or 625 #2 side will not work with a IR remote.
i would say the best thing to try for you would be to run both the #2 video coax, and the remote jack coax into a splitter, then hook that to the wire going upstairs, then upstairs, have another splitter, one side going to the tv, and the other side with little UHF antenna on it.