thanks for the help. i was wanting to find something that has Most of the components already. My dad would be the one building it, which he could basically build anything but I want to keep it simple. I've looked at those toro dingos and they're going for roughly $6000+ And that's on the low side.
You're right though about the rental. I am looking to see if I can find a place around me that might have a small unit such as a tracked concrete carrier. The only problem is I wouldn't be able to try it myself without a remote-control.
curiosity more than anything at moment for me.
all the listings for like rental place, was more about trying to "find something" that has tracks. then going back home and internet search the stuff up.
some quickly copy / paste, and edit pictures, to get idea across.

1 to 2 times a year, there is normally a "large agriculture machinery" auction near me. that blow most of the consignment auctions away, with enough stuff were there is 4 to 5 auctions going on at the same time at the same place. many times i see used mini ex and skid steers going fairly cheap.
figured since no one will be seating in the machine, you could chop off all the roll bars, dash boards, levers, joy sticks, pedals, panels, insulation, lights, etc... to just have the motor and tracks. and then setup all the things that use to be control by joysticks, levers, and pedals, with remote control stuff.
after looking at video, i quickly caught on, of having "tracks" and more so the bar that swings around entire machine, would come in extremely handy, to rotate the power unit/machine, so you could correct things. ((trying to judge distances from afar and counting down them inches trying to get up near things....)) hence the light blue thing in the edited pictures
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only issue, would be is visibility, and trying to see what is going on from afar and trying to see around a larger unit. *frowns*
and i am guessing you are wanting to deal with a smaller size engine. and as low as profile as possible? to help with visibility?
besides above, personally was thinking if you hacked at a mini ex, and had engine problems or track problems you could get parts for it. vs custom building everything. beyond remote control, that dealt with valves and like.
mini ex would most like have an alternator and battery already on unit, to power motors, electronic actuators, and small motors for remote control.
the do sell buckets vs backfill blades for mini ex. or most likely be able to even modify a small bucket for in place of backfill blade.
issue of "gas" or diesel, a larger gas tank would most likely give you a good amount of hours operating it, and relying on someone to constantly fill machine up would be much less. a mini ex should go for a good amount of hours before needing a refill. without need of putting in a larger tank.
perhaps using a generic remote start from a vehicle. that many folks have on there key ring besides the key to unlock and to start the vehicle. but use it on modified machine. to turn it on/off, without needing to climb up on the machine to get it started. (perhaps you or your dad already has something figured out for that for remote control)
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one last thought, remote control planes, that has wireless video. ((there was a thread going last month or so)) the planes with wireless camera got rather expensive, and operating time was like 15 minutes. due to how much fuel or battery life. but being that you do not need to keep a plane up in the air, and the engine on the machine can produce more power and electricty for longer time. *shrugs*
heck get a wireless network camera with titlt/angle control, and most of them run off of 12V anyhow. and use a converter between 110V to 12V. set your lap top up in front of you. along with your wireless remote.