Remco makes 3 products to make a non-towable towable, I have used 2 of them.
The Drive Shaft Disconnect (RWD)
The Axle Lock (FWD)
And the LP-1 Lube Pump (Many different vehicles).
The axle lock worked very well indeed.
However it won't help you and it's not usable on my current towed so I had to go with the LP-1.
I have heard stories of lube pump failures but, this is a guess, I think Remco has made some changes,, The unit I have now is as close to foolproof as it can be made.
Your estimate of the installed price is very close, I think mine was 16xx installed by the way.
NOTE: You must have tow lights on yoru towed as well.. The lube pump includes a tow-light and umbilical so you do not need to buy these.. In my case it was of the "Add-a-lamp" type but the instruction manual for the LP-1 indicates a universal diode kit.
Operation and installation.
They drain the transmission, remove the pan, drill a hole and install an outlet for the pump to suck up tranny fluid, re-assemble and re-fill.
They cut one of the transmission lines and splice in a "T" fitting (I suspect it contains a check valve as well). this gets the pump outlet, there is also a pressure switch in the line.
Inside the motor home is a box. It has a switch, a light and a sonalert (Noise maker)
Motor home engine switch off: Box is dead
Motor home engine running (Key on).
No car Box off, Silence. No light
NO Car, box on, ALARM: Red light
Car, box off, ALARM: Red light.
Car hooked up, Box on: Silence and green light.
Only problem.. The umbilical had a shorted connector on it, Dealer fixed at time of install.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times