[swordtart]

I'd also agree with the above.

In the past the rules would say that "you can't..." when what they really meant was "it would be unwise to...". Not so much prohibitions as serving suggestions. The exceptions to standard rules should be minimal and only where wholly justified, otherwise it just adds confusion and causes arguments.

A dropped MD on the front left (say) of a semi-trailer will probably trigger when the back half of the trailer runs past it, so it's easy to say that you "can't do it". But once you got new ammunition (e.g. radio-detonated) and modes of use, then that initial judgement starts to fall apart.

Even extreme examples like... Under-body mounted MD, madness... unless that MD is dropping radio detonated mines instead of contact detonated ones. ...SD if you have truck solids ...Oil if you don't plan on making any sudden turns... even FOJ or FCE if you don't mind being caught in your own fire.

It makes zero sense for smoke which is completely harmless.

I wouldn't treat the front four facing of trailers any different to any other facing as far as weapon mounting goes. Maybe the front underbody needs a little consideration because of the kingpin and fifth wheel interaction, but I'd hand-wave that away as an engineering problem that would be solved with sufficient application. If front underbody isn't protected from mines by the back of the tractor unit, then it is sufficiently exposed that you can drop weapons from it as well.