The 2 wingers can be deployed close to ST region and play as 3 STs if needed (for opponents who play 2 DCs with fullbacks pushed very high up). Experienced managers usually would not set up fullbacks so dangerously when facing ST + 2 wingers - deserves a heavy loss if being so naive.
The exact positioning of wide forwards is more of a personal preference. And actually players position choice at auction and gameplan are involved. I will explain my setup of 4-3W-3W and the related training a bit.
When playing 3 front players looking to maximize the pressurising of opponent’s defence, which would enable both wide midfielders to take full advantage of both flanks’ space (ST a bit forward to occupy DCs, wingers at the corner of box to be further forward than fullbacks to push them back but slightly behind DC-alignment to avoid offside), shooting ability from range by wingers and wide midfielders is where the battle is won even when opponent’s defenders could be very good.
And that is also exactly why all my wide ML/R must also have addition position of AML/R. The reason is shooting & finishing are grey for wide midfielders but white for wingers. Attacking drills of PGS & Fast Counter-Attacks alone are already enough to make ML/AML(R) deadly (especially efficient for lower level managers who may not have all drills levelled up or learnt yet).
[MC/ML, a 6* player reward from event, in the image is not my preferred choice of midfielder - MC defensive skills + ML wide midfielder skills are nearly the exact opposite, hence making a player being average. He is in the squad purely because of 1* better than the rest except key players. Own preference of multi-roles are MC/DMC, ML/AML(R), DC/DMC & ST/AMC as main white skills are mostly overlapped and the flexibility of turning into defensive without subs to defend 1-goal leads very efficiently).
The other point is about the 3 MCs in a 4-3M-3W setting. MCs do not have crossing ability (except with multi-role with ML(R), which makes the midfielder average as above), so placing MCs close to ML or MR region are not preferred because they would keep wasting attacking chances by rubbish crosses when attacking via flanks. Keeping 3 MCs tight in the middle forces the engine to enable their passing abilities more, and so playing with AML & R in default positions in a 4-3M-2W-1 via flanks would be better. Similarly, when 2 wide forwards are played as aligned STs, keeping the 3 MCs tight in the middle and attacking via middle would have a better result.
Only exception is when we have 2 of the 3 MCs have ML & MR roles too and also we have a 10%+ quality advantage over opponent’s MCs, then playing both MCs close to ML & MR would both dominate MC areas and also assist efficiently via wide areas via attacking flanks. Implementation of this should have started with players acquisition in auction already, though this setup is really T-expensive.