Yes, removing secondary mirror and replacing it with Hyperstar is easy and you won't lose collimation.
Remote control.....arrgghhh.....yes....but I over engineered this!!!!!
I was initially obsessed with 'wireless' and 'cordwrap free', but my camera exceeds 4k UHD and I also wanted to hook up to a 4K UHD monitor. I succeeded by putting an Intel NUC i5 with Iris Plus 640 Graphics at the scope and another NUC indoors, the latter controlling the former via Windows Remote Desktop. To get there I had to resolve a bucket load of challenges, but I did produce an 'end to end' 4K UHD wireless system. However, despite having invested in the highest quality components and establishing a 'peer to peer' 5Ghz Astro dedicated network with no external interferences I still suffered from occasional frustrating 'lag' and less frequent 'drop outs'. The danger with this is the risk of a wild uncontrolled slew and potential damage to one's rig.
Wireless using Windows Remote Desktop (or TeamViewer) works fine with (say) 1080p 'HD' cameras, but step up to a large sensor, ultra high definition 'UHD' (4k) camera and frankly, current consumer wireless technology (802.11ac) is unreliable. People pursuing these ambitious goals do need to understand the limits of current connectivity technology (or not buy the highest resolution data intensive cameras) for EAA.
I then replaced wireless between the two NUCs with 'active' USB3 cable. Works fine, but only up to about 10M. I also suffered conflicts between USB3 and USB2 devices. So I then switched to a 20M Cat6a cable and that works perfectly. However, rolling out the Cat6a cable on every use soon puts kinks in it and it becomes ever more tricky to coil after use. It's perhaps better for a permanent observatory as I am not convinced how robust it will be if in daily temporary use. However if you require perhaps 30M distance or beyond, it is arguably the only solution if your camera data transfer demands are extreme.
Here, Astrophotographers will be quick to jump in and say that you only need a high powered computer at the scope as you only need use the second computer to control the former and any post -processing can be done on the primary. That is absolutely true for AP. But for EAA the objective is immediate 'near live' viewing. So if you want to benefit friom a 4K UHD display (monitor), the computer at the terminal point of the system must be 4K UHD graphics capable. Hence, one is squeezing 4K UHD screen data down the wires. EAA and AP demands hence differ if you seek 4K UHD. I would add that 1080p EAA is great, but what is the point of buying a 'UHD' camera to output to a mere 'HD' display? Also if you embrace Hyperstar, the higher <zoom> capability of a 3,840 x 2,160 display is beneficial as the benefit of a 5x increase in FOV is at the inevitable cost of a reduction in magnification.
Eventually (and this will sound utterly stupid given the complexity of earlier efforts), I tried running a 20M (65 feet) HDMI cable from the NUC at scope direct to my monitor indoors. I now control the NUC at scope by a Logitec wireless keyboard/mouse which has a truly remarkable range. This works just as well as any of the above up to 20M and saves the cost of a second computer. But over how much further distance a HDMI cable will work beyond that is debatable. However, it's so cheap I would try over your 85 feet. Frankly, I went down this low cost route after belatedly discovering that you NEVER actually need two computers as a single computer plus mere 'AV/HDMI extender' using cat6a works over quite long distances. Until then, the simplicity of attempting wireless mouse/keyboard and HDMI didn't even cross my mind. Now I have a surplus NUC, but will find an alternative use!
In summary, don't be lured into the wireless/cordwrap free paradigm until you have really thought everything through. I totally over engineered things and wasted a tonne of money. However, I suspect that my experiences can benefit others. Best of luck!
Lastly, I am sure a GEM is beneficial if you want to win Astrophotographer of the year and sit for hours chasing a single remarkable exposure. But you enquired about EAA where an Alt-Az + Hyperstar is far easier, is light pollution beating and is about near live observing, and not about taking pictures (although you can). Unless you want to get drawn into the dark arts of AP there isn't any need to fall into an even deeper money pit (yes, been there too with my wedge!). For EAA you don't need polar alignment or autoguiding, just a few stacked 20 second frames even to view the Horsehead. But if you want an award winning image, then you may need long exposures.
Edited by Noah4x4, 10 January 2019 - 02:45 PM.