Don't like this talk of a 45m/140' dive on a single with no redundancy. At that depth the rule of thumb is 1:1 bottom time to deco (longer deco times if on air!). Thus any dive to that depth must factor in decompression. Also, at that depth narcosis is very real and affects everyone. You train yourself to be competent(ish), but you're still affected.
Anyone can do bounce dives like that and most will live to tell the tale. However, if anything goes wrong or you're slow off the bottom, you've absolutely no contingency to handle it and worse still no redundancy should you loose gas. A bolt to the surface from there is pretty much a sure-fire guarantee of a trip to the pot (recompression chamber) -- if you're lucky. This is the classic "Divers went missing on a dive" story -- often described as "experienced" divers.
Why not dive with two cylinders? This can be either a proper manifolded twinset (DIR style), or a pair of singles clamped together (run as two singles with separate SPGs), or a couple of cylinders sidemounted, or even a single on the back with a pony-rigged ali80 as a stage on the front. This will give you the contingency and some redundancy to be able to do limited dives which is a massive weight off your shoulders -- and your buddy's.
Of course the best way to do that dive is with mixed gas and oxygen-rich decompression stage(s) -- typically a twinset with ~20% helium and one stage with 80% or two stages with 50% and 80% (other mixes are available). Then you could have over an hour on the bottom with a runtime of just over a couple of hours with stacks of contingency and redundancy. You come back relaxed and you remember the dive (helium, the gas of the gods). (Won't mention rebreathers -- they cut gas costs to a fraction of open circuit)