First, let me say Thank You to those of you that have replied with suggestions to help. Believe me, I really appreciate the suggestions!!
When I had this doublewide set approx 6 years ago now, I wanted to not only have it qualify for "regular" site built homeowners insurance, but also wanted it to be as safe as possible. As a result, I had the ground dug out that was to be underneath the home to about 2 feet deep, and then had 53 piers drilled on which the frame of the house would sit. When I had those piers drilled out, they were 18 inches wide and 5 feet deep, and when I poured the concrete into them, I also then had steel put into the wet concrete. When all was dry and the home was set onto the top of thso piers, the stell was then welded to the frame of the home. At that point it qualified as a site built home for insurance reasons. Since I live right in the middle of the Barnett Shale, that means I have a lot of fractured rock on certain areas of my place and my home is right on top of one of those areas. By digging down that 2 feet initially, I basically eliminated the fractured rock from under my home and I was left with nothing but solid rock under and immediately around the edge of my home now. It is great for safety reasons, ie; the piers, welding etc, but severely limits other things such as anchoring any "normal" track for the underpinning. Basically, that's why I've been having so much trouble with this lousy, cheap, vinyl underpinning like I've been having. The bottom track can't be anchored very well in the solid rock and keeps coming up, thus allowing the underpinning to get torn apart with any wind whatsoever. I'm only mentioning this to further explain my situation and possible problems .
Bird,
Thank you for your suggestions and that site location.
jinman,
Jim, thank you for that info on Lowe's. I'll go check them out and see what I can find.
Phils,
I saw how those disgarded garage door panels looked and honestly, you did a real fine looking job.
JJT,
I'll check on the price of that rough cut pine too!
In general, my problem will still be anchoring, on the bottom, whatever I decide on to use as an underpinning material. The groove cut into the landscaping timber is a great idea, and I hadn't even considered that until y'all suggested it here. I can't use rebar because in order to get the rebar into the ground far enough to hold, I'd have to use a "puff drill" for every rebar piece. The only alternative to that I can see is to use something on the bottom heavy enough to hold, without the rebar having to hold it in place. I'm not sure those landscape timbers would be heavy enough. Possibly combined with a heavier underpinning material, like one of those already suggested, it might just work. I need to go check it out at Lowe's and see.
I REALLY appreciate each of you taking the time to reply with your suggestions as I was getting frustrated with the present situation very quickly!! I'll let you know what I find!!