Halp. Adjusting a stock seat beyond its standard range

I'm pretty tall. As a consequence, in my DD (2012 base Highlander) my thighs don't touch the car seat - despite the full range of adjustability of the seat. Some cars are better than others but this is mostly.. uncomfortable. 

I'm thinking about trying to make or buy some wedge shaped blocks to place under the four seat anchor points. The back ones would be very thin and triangular but the front ones would be taller - to allow the front of the seat to be a little higher and hopefully pick up some leg support.

I don't own a any precision metal cutting tools so I am considering using a source like send-cut-send.com to make the blocks but I know nothing of metallurgy.

I'm also not sure whether longer bolts (what grade?) would make this dangerous if I got in an accident. 

I have not yet drawn anything in cad but I'm sure the seat bolt screw bosses are part of the floor - so shimming and angling the seat means the bolt head will no longer make proper uniform contact against on seat "leg" so I might have to elongate the hole in the seat and add a shim on top as well to allow the bolt head to have uniform support.

I tend to drive with the seat back pretty upright - not leaned back - and I realize this would change the seat back angle. I'm not sure if it would have any negative impact on airbags in the seat. The seats aren't powered and have no heat so I believe there is no wiring to worry about. 

What other things should I consider? I appreciate any thoughts or suggestions on the material and the bolt type.. any anything else GRM has to say. Go!

Is the seat base angle adjustable? If so there's probably a front pivot point within the seat frame that you can raise. That should be simpler and less structurally questionable than messing with the floor mounts. I actually just did exactly that on my cayman and it's worked out great so far.

Is this what you are wanting to make?  I have these for my Land Cruiser and they make a huge difference.  
 

www.desertdoesit.com 

dps214 said:

Is the seat base angle adjustable? If so there's probably a front pivot point within the seat frame that you can raise. That should be simpler and less structurally questionable than messing with the floor mounts. I actually just did exactly that on my cayman and it's worked out great so far.

I don't understand what you mean. The seat pivots from the back so the front edge goes up and down - it's just made for people of normal height, so it's not adjustable enough. 

Sketch 

Caprigrip said:

Is this what you are wanting to make?  I have these for my Land Cruiser and they make a huge difference.  
 

www.desertdoesit.com 

This looks like what he is describing.  I'd do this and call it good.

Caprigrip said:

Is this what you are wanting to make?  I have these for my Land Cruiser and they make a huge difference.  
 

www.desertdoesit.com 

That looks like exactly what I need. They don't sell one for my generation of vehicle unfortunately. I will contact them!