Fuel tank under bed

[Swedchevy67]

Need some suggestion about putting the fuel tank under the bed WITHOUT removing the bed.
On my 67 I removed the bed so it could be better to replace the fuel tank, but now on my 69 I’m not so hungry doing that job, so my plan is to cut out a peace of the steel bed and do it from there. To protect it from the outside I will replace the cutting peace with a new top (don’t know yet with what).
Any pictures and information will be much appreciated.
Merry Christmas 🎅