Re: small Stonekeep and its roof
1. Lock down snowpile.
2. Raise snowpile up/down where you want the goza.
3. Place rune on top of snowpile.
4. Lock down rune.
5. Target the rune with the goza deed cursor.
6. Repeat as necessary.
Note: this works for any house add on that comes in the form of a deed. However, an anvil takes just one tile, but a bed or abattoir can take up to 8 tiles and as such required 8 snowpiles/runes, one for each tile the add on covers. You'll need to line up the snowpiles at the correct height and target the right rune in order to place the add on.
This can be used for all kinds of stuff, including stacking player vendors or house addons on top of each other (have to make a goza staircase firs for the first option). If you remove the snowpiles/runes afterwards they float in the air, same goes for house add ons.
However, been trying extensively to get on my castle roof with a goza stair case and it just wouldn't work as one crucial tile near the roof blocks the placement of a goza, and you cannot teleport on top of the roof as far as i know.