Spring is almost here and I'm trying to put up another antenna in my yard. ... I operate 99% of the time on 40 and 75 meters at night.
I think that the key to any antenna selection is your above statement (99% on 40M and 75M).
Yes, verticals close to the house will work as WX7G inferred. And 270 degs of radials is much more than many other ops, including me, have.
Your choices appear to be a dual-band ground mounted vertical or the possibility of some kind of horizontal loop antenna; the vertical is probably the better choice given all your parameters.
A full quarter wave vertical for 75M is ~ 65' tall. While not impossible to erect, one needs a guying mechanism (perhaps two levels of guying), so most ops in your situation would go for a loaded vertical that is a compromise height, say, 40' - just like your wife likes
Radials can cover the full 270 degs; since they will be buried, the length isn't critical, but shoot for several dozen at least 40' long. (If you have the capability, then my all means lay down 45 radials (15 in each quadrant) and make them long, 65' is about the max length.
The flower bed concrete border (concrete, not cement; cement is a component of concrete) shouldn't pose any problem except the extra work to dig under the boarder.
The rain gutter (or do you mean downspout [the vertical portion]?) may present a problem as it is very close (electrically speaking) when you're talking 40M and 75M. Lots of folks simply replace the metal downspout with PVC. The rain gutter (horizontal part) shouldn't be an issue even though it also is fair close.
There are several methods for loading a vertical. Start by studying up on coil loading at the base and at the center. Then take a look at what is called a capacitive hat. See if this is something that you think that you could do. The right combination of a 40' vertical with loading coil and capacitive hat and good radial field will provide you with many hours of worthwhile operation.
GL 73 Rich K3VAT