ideas for curinslight weep on inaccessible compression joint

In readiness for new kitchen I was re-routing the feed to downstairs hot water as it ran down the middle of kitchen wall. Due to access issues I chose to use compression joints on a certain elbow as I could do up one half before sliding pipe in place and just reach other half when in place.

So problem is that initially no leaks after turning water on, but having been left for a few hours there is a very small weep on one 22mm elbow joint . And obviously it's the inaccesible one . Pipes in front and wall behind means only access is from end. The weep is very small and in normal circumsatnces less than 1/4 turn would probably cure it. Obviously when hot water run, the leak goes (well probably water just evaporates, but you know what I mean)

Any idea how I might get in to tighten, or seal or take chance taht as it's small and on hot water, it will soon seal itself with scale

cant you get a screwdriver in and give it a tap with a hammer , as you say jjust a slight turn will normally do it.I have to undo loads of fittings with a screwdriver and hammer,when its impossible to get at with spanners,is it a real conex with the lugs on the nut on or smooth ,

Hate to admit it, but it's a Homebase special as I forgot to go to the plumbers merchant before they shut, so smooth.
If I was undoing it I might take the chance, but tightening without anything for teh screwdriver to press against might e a risk too far. Reall don't wan to have to dismatle most of my work and start again for one small weep, but I guess I may have to

Anyone got any other ideas?

is there space to get an adjustable basin wrench in ?

Unfortunately no, I even bought a smaller one than I had today to try that but no luck.

I am thinking of getting some Fernox ls-x and giving that a go before dismatling

thanks for the ideas.

How about these?