In general, you are talking about something on the order of 150 feet, give or take. That's not necessarily in a straight line, but can be 'bent' in a number of interesting ways, and includes the space needed (taken up) by the support thingys. For a 'straight line' type antenna you can sort of figure whatever it's length is (typically 1/2 W) and then add something like 20 feet for those 'thingys' like support ropes, insulators, and who knows what else.
How high should it be? As high as you can get it. That usually means a minimum of high enough so that you don't 'clothes-line' yourself on it. A rule of thumb is that if it's high enough that you can't really make out the wire up there, only the feed line running up to it, then it's 'close' to 'right' (a little bit more might be better), sort of. Lots of 'wiggle-room' there, this is all just a generalization. It applies to all antennas, not just the 'Windom'.
Working 'backwards' helps sometimes. Figure out the length of the antenna, add a few feet for a 'fudge factor', then see if you can make that 'fit' the room that you have available.
- 'Doc
"Ideals" are things that people 'strive' for, very seldom ever reach, but are the 'goals'. The 'best' that you can ever expect are 'good enough' results that allow you to do 'almost' everything you want to do. The -Best- is a combination of physical attributes and ability. What you lack in one has to be made up for by the other, and that result is your 'best'. All men are created 'equal', but from there it always changes.
Hows that for a 'philosophical' moment?