I need help making my LL Airhead a little better fit. I have noticed when I start going a bit harder I really move around a lot inside. Also I don't think its a good thing when you start to slide out when you go upside down is it??

My dimensions are 6' 190#
I would also like to be able to either make everything or be able to buy it at any hardware store or such. Super cheap here!!
So far I've got:
1.Put in hip shims and pads. I've got the self adhesive pads that came with the boat but they over hang a lot on the post that they go on. Any ideas on how to solve this?? Or better alternatives that cost very little(I mean super little) and require not ordering anything.
2.Move the foam bulkhead forward about 4-6 inches.Not really much help on this one but if you've got any ideas don't hold back.
3.Create better thigh hooks. Maybe shave a couple of blocks so there are like pockets for my knees.
I had no idea what I was buying when I got it, And knew nothing about the sport when I made the purchase. I wish I could get a new boat but for now I've go to make this work.
I would like any ideas you have
I expect the almighty buzzards to prove their expertise in kayak outfitting while keeping the costs down. I know there are a bunch of you cheap boaters out there.
Thanks for anything you can help with,
Luke