Rhino Support?

Don't forget the Hydra/spiral variety. Excellent for trolling and hard to kill.

This answer is what the OP asked for... support build.  Cheers for that gr3ygh05t.

Another one that doesn't get a lot of play or love, is the Molot + Molot Mk 2.  NOT the best build, but if you play it right, not horrible, either. Many folks run the Griff with this build... but the Rhino has been associated with close in scrapping for so long it rarely enters most folks' minds. If you try and keep good elevation and an eye on the opposition, you can do some real good work on Furies and Griffs and other unshielded bots from outside their range, while being able to shield up to block Treb fire and other Molot return fire.  It is also decent for hitting Ancile bots and draining them for your team mates to hit with their damage dealing weapons.

A close-in support option is the Punisher version of the above bot.  It is absolutely an Ancile eraser, and the spread of the cone of their fire will do a good bit of good against shielded bots as well... since you will be hitting the areas of the bots not covered, as well as hitting their shield.  Up close, they are like thunders in their output of damage.  Again... as a SUPPORT bot, this would do well... you are NOT trying to go toe to toe with knife fighters.  The goal is to roll with a KF and maybe run slightly behind and to the side of them so that you can swing in on the flank of whatever they are fighting.  Especially if they are fighting Carnages and/or Ancilots.  This is another build looked at with disdain on the Rhino but is very respectable on the Griff... *Shrugs*

Besides the Hydra spiral that was mentioned... the Hydra Aphid could be a variation that still works well at 350m or less to hit stuff from behind cover with a bit more punch when they get too close.... just a thought.  

The RDB is probably the most effective overall... you won't have the jump that allows you to re-position or to pop out of cover and land behind more, but you can shield up and move away at a good pace, especially if you are leveled up to a decent level.  Some folk like to run short range weapons on the light spots to make people ignore them at 400m... then they unshield and let loose a salvo from the Tulus when least expected... Aphids or Mags would be the best ones for this as it allows for some decent close in, shielded, self defense.

Just my alternate POV... I think the amount of firepower the Rhino offers is so often ignored bc it can't hang in the fluid and more agile brawls that they used to be the kings of, without considering how the mid-range support role may actually do it justice since the lack of mobility doesn't impact you as much at 400m - 800m.  Yes, Tridents and other RDBs/Tulu builds will hurt, but you have a pretty good HP pool to absorb a little bit more of that damage than the Griff of the same level. 

It may be a wast of effort... IDK, I have ran these builds on the Griff, but only the RDB on the Rhino... but I would think that if you can keep it in mind that it is NOT a KF setup, but instead a mobile MR platform, you can adjust to the build that you decide to try.  Would take a bit of figuring out where the Rhino would work better at with this type role on every map.  Either that or get on the TS and buy a hangar of Rhinos and MR support weapons and test it there... depends on the things being tested though... some TSs are not at all good for deciding on something you would use on the Live server.

IMO, YMMV

That last part proves its worth though!  Not that I could play it and still look in the mirror, afterwards