You came up with a solution and it looks pretty good.
One concern with portaflex amps in general, is that when they are flipped, during transport the head as some wiggle room. You see a lot of B-15's with dents in the transformer cans from hitting the speaker magnet.
So it's important when space is tight, to allow for a small amount of movement inside the cab. If it is an issue, in some cases a mouse pad or a piece of thick felt can help protect things when transporting the amp.
One concern with portaflex amps in general, is that when they are flipped, during transport the head as some wiggle room. You see a lot of B-15's with dents in the transformer cans from hitting the speaker magnet.
So it's important when space is tight, to allow for a small amount of movement inside the cab. If it is an issue, in some cases a mouse pad or a piece of thick felt can help protect things when transporting the amp.