1000 ft for the 3 nm circling area would be all right, seeing as you work out your NVFR LSALT by adding 1000 to obstacles within 10 nm of track (+ unreported towers - 360'?).
The thing is getting down from there to the strip. You need to have surveyed it, or trust someone who has - ie. from the threshold looked back up the approach path at a suitable angle with a suitable splay ensuring when you're coming down finals at your normal approach angle there's a good clearance between you and the highest obstacles you could possibly meet.
A similar thing needs to be done for departure / go-around areas, and engine failure taken into account if applicable.
If there are hills in the circling area, you might be able to reduce your circling altitude by using one side of the circuit only, with an allowance for 'straying' onto the wrong side by a few degrees on finals / overshoot.
If there are significant features, you can find yourself at quite high circling heights and therefore a steep approach path (about 300 ft per nm for 3 degrees) so you might have to extend the circling area out accordingly.