saddle tanks or what?

[Dwaynes56&68]

I already did the blazer tank conversion and removed the tank behind the seat. But now that i have bought a travel trailer, more fuel capcity is needed. Does anybody know where I can get new saddle tanks that fit a short bed? I was hoping there are some urethane replacments but have yet to spot some and all the ones in the wrecking yards look to old and rusty. I cant give up what little bed space I have so a transfer tank is not a good option. Thanks for any help.