i call BS on the 8000ft sighting.. with a max climb rate of about 400ft/ min, and a max battery life of about 15 to 20 mins.. not to mention a loss of single safety kicks in about 1000ft away...
The small to smallish types, perhaps yes.
However the next level up in expense and sophistication (and not all that large) are quite capable of reaching 8000 and higher, have quite good battery life (technology is improving all the time), and also have the smarts to be programmed to track via a set of lat/longs, do things enroute (e.g. take pix) then return to a point of origin or somewhere else and land.
Legally, such ops being above 400FT and beyond VLOS require prior CASA approval of course, and they would issue a NOTAM.