Removing this requirement would allow competition (even from independent researchers in coffee shops).
Good luck trying to change this!
An endowment you can rustle up with sufficiently well connected people, especially if you aren't looking for that much money.
Grants I agree are a problem. Darpa as I recall doesn't necessarily require university connections, but I'm not sure if Europe has anything easy like that. Maybe you attach a startup incubator?
1)https://www.patrice-besse.co.uk/ads/historic-buildings-for-s... 2) https://www.patrice-besse.co.uk/ads/historic-buildings-relig...
EDIT: In terms of financing, how much money do you really need? If you are self sufficient in terms of owning the property, endowment income and growing vegetables and selling beer/yoghurt etc., is that not enough? Would the modern academic type be interested at all in essentially living in a commune/monastery where some amount of time is dedicated to cleaning/maintenance/carpentry/agriculture?
Universities are hard due to accreditation, but starting a not-for-profit is quick and easy.