Martel-Stansby among others play a 3-way signal in this situation:
low - encouraging, but don't make attacking shift if A stiff
middle - encouraging, but do make attacking shift if A stiff
high - discouraging
I may not have been clear. 1♦-1♥-1♠-2♣-2♦-2NT is all balanced invites, not forcing. 1♦-1♥-1♠-2NT forces 3♣, either weak with long clubs, or GF with 5♥ 4♦. The rationale is that going through 2♦ GF you may have some ...
I play a Demirev treatment:
all balanced invites go through 2♣-2♦-2NT.
2NT forces 3♣ for signoff, or if bidding on, it shows 5Y + 4X GF, and none-low-high shortness.
For example after 1♦-1♥-1♠-2NT-3♣:
3♦ = 2542
3♥ = 3541
3♠ = 1543
Possible, though opponents would have to be at least somewhat out of line vulnerable to be competing with 8 trumps and no points. We haven't shown GF values, and they know they're putting themselves on the chopping block.
They might have a cheap save so it's good to take up some space here. If we were playing Bramley's one-bid, I'd guess to bid 6♠, but here it's just too likely that partner looking at ♠AK ♥A would raise to 7. So I content ...