Hi Paul! First make sure the width of the MX5800 will fit in all the places you want it to go (use a piece of PVC cut to length). If it will then you have the right size! I like all of your attachment choices just remember that with the LP QH you are going to be getting all LP implements that fit it. There are no standards for QHs so you may not be able to use other manufacturer's implements. You could forgo the QH and BB...getting top and tilt kit instead. The top and tilt will require the extra rear remotes, so make sure you get at least 2 for it. If you want a hydraulic angle blade and top and tilt, that is 3 remotes. I went this route over a QH and BB...will see how it works out. I have the same HR 3584 with hydraulic angle as TripleR....its a nice setup.
For stumps...absolutely wear someone else BH or excavator out. I have a
M62 and I am not digging stumps much either.
If you aren't snow blowing or mowing you really dont need all of that HP. I would even look at the MX 4800 (non turbo) where you are at sea level as an option. Spend the money on implements, rear tires ballast, etc.
If considering a skid steer...I would definitely consider a tracked loader...and they get expensive quick. For that reason I think the MX4800 give you more flexibility. Rent a SS or mini-ex as needed for specific tasks.