I've seen all the wonderful Snake roll variants, the voodoo's and whatever... They're always demonstrated (online or in videos) by a caster standing in the water with room for a good sized D loop behind them and the anchor just in front of them. Oh and usually into a river with a gentle current and few snags. Honestly even I can look good in those circumstances.
If I'm lucky enough to be in that situation I can put the fly anywhere I want with a roll cast either type of spey or at a pinch a snake roll, but I've a lot of free access to what is pretty difficult water to fish so please good people help me with a cast for the following situation...
- High steep banks so you have to cast down at least 4ft below the soles ofyour shoes before you touch the water.
- Water depth dropping away so unsafe for wading and you have to stay on those high banks.
- Overgrown so there's little room for even the D loop of a rollcast behind you.
- Still-water so you can't rely on the current taking your line out and then simply use a change of direction cast for the next presentation. You're going to have to shoot line each presentation.
Fishing the margins is fine, well sort of fine, I lose flies and do get the occasional tangle

but it's a case of stalking, dapping/lowering the line through the brush, snap c/t's etc. but how to get the line out? My rolls in these situations are rubbish. I think it's because I'm so high above the water that I can't get a tight loop rolling out to carry/shoot line and trying to shoot line with such large loops means that turnover is poor which compromises distance anyway.
Trying hauls with roll casts when casting such large loops isn't productive... on the backcast I'd just shoot line into the D loop behind me and risk catching vegetation, on the forward the higher line speed doesn't seem to make much difference to the large loop.
But I confess I am a little confused because longer rods with bigger D loops are supposed to roll better... Maybe it's important that the the rod works the whole of the loop? In which case a 7ft or 9ft rod trying to cast a D loop 11ft or 13ft tall isn't going to be able to cope? Maybe I just can't roll cast well enough... ?
Crouching/sprawling on the bank to lower my height above the anchor seems to help a bit, but not enough. Before I give up and go for a bubble float and a few flies are there any casts that can carry some distance and shoot line while keeping <b>all</b> the line in front of you? A mate suggests something called a Tunnel cast, might this work?
All suggestions welcome.