Which lightweight 4/3 primes for video for Botanist with hand problem

Hello Folks!

I'm hoping for some advice before I purchase a prime lens for my new GH4. My needs are pretty specific:

Must be lightweight, under $1,200. manual aperture and focus, and ideally a declicked lens. I have one purpose for this lens and one purpose only: I want to do hand held shooting of tree and shrub foliage at the local Aboretum. Due to a hand disability I can no longer operate my tripod or hold heavy gear for handheld shooting. By way of background I'm a newbie shooting video with primes, but experienced with my long time Sony Camcorders. I can no longer do handheld work with the Sonys and have recently purchased a GH4 because it is lightweight. I've mounted that to a Cotton Carrier vest with "steady Shot" platform so I have hands (particularly thumbs) free and can operate the iris and focus with my fingers.. I was looking at a set of Rokinon prime Cine lens but they are very heavy. Salesman at the local camera store suggested instead a set of Rokinon's that are made for still shooting: native 4/3 format, 1/3 of the weight. The downside is that I'd have to have them "declicked." I can't imagine shooting without a smooth aperture, but the procedure will void the warranty and I can't imagine buying a set of these without warranty. The primary shots I want to get will be as close as possible of foliage, bark, leaves and flowers. Since the lens/lenses I choose will not have image stabilization, (  do plan to learn the Warp Stabilizer effect in Adobe Premiere pro shortly.... so that can be taken into account as well) I'm concerned about the maximum effective focal length I should choose relative to camera shake as the workhorse lens. The vest rig I have is pretty stable but no gimbal, I have a lot of experience shooting steady with camcorders, and I mounted a Zacuto Zfinder to the GH4 so I have another point of contact on the face. So, folks, I'd be grateful for any lens suggestions, comments on declicking (what can go wrong besides the warranty going south?) and maximum effective focal length experienced 4/3 shooters suggest? A fast lens would be wonderful, but no deal-breaker. Close focus or macro even better. Weight is key. I have a Canon 5Diii I use for shooting plants in the "studio" with Canon 5x macro and the 100mm macro, beasts all. If I need long shots or medium shots in the field I can have a helper set up the Sony or the 5D on a tripod. Did I mention the main use of this lens is to go close along branches and foliage--- panning down a given branch and focusing and adjusting aperture as the camera slowly pans along the branches....My cell phone can do this beautifully.... but the footage is garbage when blown up for screen of course..... there must be something out there for me? Any help would be really appreciated. -Thanks!