What an idiot I am … I forgot to slide the tank before closing the cockpit … I only realized it last night and it really kept me awake. But what an idiot I am. I should had to slide the tank through the cockpit by the firewall bulkhead. Anyway, the cockpit is finished and last night, I realize that I didn’t put the tank in.
How to do it now? You can see on the pictures below that there is no place to slide it from the front or the top.
I really need your help and advice before doing anything and especially not to do anything stupid.
First possibility: Remove the engine mount, make an opening in the bulkhead firewall. Slide the tank into it. Make another (thinner) bulkhead that will be glued on the old one and put the engine mount back on.

The second solution: Cut the stringers behind the bulkhead. Place the tank and come back to put the front part back in place, doubling the stringers of course. This would be the fastest solution, but will it be strong enough afterwards ???????

The third solution would be to cut only the upper spar and then insert a tank placed at 90°. However, I have never seen a tank positioned this way. Is it possible? Or are there tanks with the hoses positioned in the center?

I really need your advice and maybe another proposal. Thank you in advance.
Hi,
May I suggest the following –
1. Remove the engine mount
2. Make an small opening in the bulkhead firewall, just about the same size of the tank
3. Install the tank, make sure you consider the fuel feed tube hole location
4. Use 1/16″ ply to make a replacement bulkhead for the tank side to overlap the opening. You may need to cut the ply
as a left and right half to get it inside
5. Glue back the original small cut-out piece of the bulkhead
6. Use another 1/8″ ply to add onto the bulkhead for the engine mount side
Thanks a lot. It is the solution that I was thinking. And what is your opinion on a plastic soft bag ?
There are the 2 solutions I have in mind presently
ELECTRIC
No way, I wxant to hear the sound of my 4stroke engine
The front/ending mount need should be strong, it’s fine now. A side access panel like a real airplane would be my pick. Major structure is there for a reason, leave it if possible, if you need to cut one something else needs to take the load (glued on doubler or plywood somewhere). As mentioned you’ll need access to the tank later so the hatch needs to be easily removed (bolt and blind nut).
Thanks Barry
Thanks a lot and thanks to all who helped me to take the most appropriate decision.