[aferaci]

Well, I was thinking of using some sort of calsil type of board for the insulation hearth but it's just too expensive. If i used that board then I could just weld a steel plate to the base and put the board on top of that, doing away with the concrete hearth.

But I think I'm just going to have to bite the bullet and do the hearth with concrete. I'm planning on putting a 3500lb torsion axle which already absorb shock and road vibration much better than typical leaf springs.

I also plan on doing a house type of enclosure instead of a dome. I will loose fill the enclosure with the perlite and that way, if the dome suffers any type of crack and needs repair, I can remove the roof, vacuum out the perlite, and make the repair and then put it all back in.