TMER&L is The Milwaukee Electric Railway and Light Company (TM for short). CERA did an excellent history on this company (TM, Bulletin 112, 1972). The information on these locomotives comes from the work equipment roster in that Bulletin.
While the trucks do resemble arch-bars, they were TM's own design. These locomotives were built by TM, and with the exception of L1, were used to haul coal hoppers from railroad interchanges to the power plant. Several of these locomotives survive in Illinois and Wisconsin museums.
Wisconsin Power and Light rebuilt a work car into a steeplecab while keeping the archbar trucks. That effort tipped the scales at 66,000 lbs according to CERA Bulletin 111 - Badger Traction. This is probably more typical than the TM motors.
I guess the moral of the story is that if the trucks are built stout enough you can definitely get into the "big critter" stage.