..............Tango , The word I would use to describe what you are wanting to do...is "Tamping". It is a viable method of setting posts in the ground, BUT....keep these factors in MIND...
1.)The "holding" ability of Tamping is contingent upon (3) factors..a.)the type of soil you have on your land , b.)the depth of the hole, c.)the moisture content of the soil during the course of the calendar year.
..............I have set some posts in the past here in Texas by tamping. I use a Rock bar about 6 feet long that has a 3 inch flat head on it as it is made specifically for this purpose. This rock bar is about 1 inch in diameter and fairly heavy as it it is made to bust up rock as well tamping. Personally, i would NOT try tamping unless i could dig ALL my holes atleast 3 feet deep. Also, the Larger the circumference of your Post(s) the greater the chances of success for tamping. If the soil is Moist when you First set your posts they will feel very solid. BUT, if you go into a prolonged Dry spell the moisture content of the soil will decrease and it will pull back from the POST and then Your once Tight Fence will be falling on its Face. Not Good......You should give considerable thought to which method you choose because....IF....you have to go back and redo and reset your corners and h-braces you will ultimately spend considerablly MORE money in the long run. Do it once ....with cement ......and walk away and focus on your next project..........fordy...

:yeeha: