(ET) elec-trak front mower capabilities?

[Charlie <medievalist gmail com>]

I'm trying to scratch up the money to buy a late model large-frame
elec-trak with a 42" front mower.

I have a 38" belly mower on a gas lawn tractor, and there are parts of
my property, particularly heavily undercut stream edges, that I can't
currently mow except with a string trimmer.  If I get too close to the
edge with the tractor, it will collapse and I'll end up in the water
or worse.  If I don't mow those edges, the annual japanese stilt grass
takes over, shades out and kills the perennial grasses, and over the
winter I lose a foot of stream bank (repeat yearly until no property
left).

What are the limitations on how far the Elec-trak front mower deck
travels?  That's a strange question but I don't know how else to put
it.  If I accidentally run the front rollers off the edge of an
undercut bank, is the blade going to get driven into the ground at the
edge, or will the deck hang out over the stream?

I understand sickle-bar mowers are near impossible to get for small
tractors these days, or I'd go that route.

Thanks in advance for any insights,
--Charlie