Ok, I have found a way to _set_ the columns/rows so for example ssh client will report the required resolution (80x25) to the server. For compatibility with some servers it might help:

stty cols 80
stty rows 25

This won't make osso-xterm display 80 columns, but fooled the server that required 80. (Actually, with smaller font this should limit the display to a 80x25 rectangle, avoiding 132x... and displaying all of it)

Another way that works, but is probably not worth it: easydebian with roxterm (bit of playing with settings, undecorating the window... slow as hell, but works). There is also nice selection of VTEs from synaptic package manager, some install without problems