Marked as 古風 in sankoku (only one sense).
The "intolerable" sense we have here appears to be different from the one on 仕方がない. It's not in the smaller kokugos, and the daijr/s examples are archaic. I think it can be dropped.

@@ -9,4 +8,0 @@
-<keb>詮方無い</keb>
-<ke_inf>&ateji;</ke_inf>
-</k_ele>
-<k_ele>
@@ -16 +12 @@
-<keb>為ん方無い</keb>
+<keb>為ん方ない</keb>
@@ -20 +16,5 @@
-<keb>為ん方ない</keb>
+<keb>為ん方無い</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>詮方無い</keb>
@@ -28,11 +28,7 @@
-<xref type="see" seq="1305420">仕方がない・1</xref>
-<xref type="see" seq="1305420">仕方がない・2</xref>
-<misc>&rare;</misc>
-<gloss>it cannot be helped</gloss>
-<gloss>there is no way</gloss>
-</sense>
-<sense>
-<pos>&adj-i;</pos>
-<misc>&arch;</misc>
-<gloss>intolerable</gloss>
-<gloss>unbearable</gloss>
+<xref type="see" seq="1305440">仕方ない・2</xref>
+<misc>&dated;</misc>
+<gloss>cannot be helped</gloss>
+<gloss>unavoidable</gloss>
+<gloss>inevitable</gloss>
+<gloss>(there's) nothing one can do</gloss>
+<gloss>having no choice</gloss>

Just noticed that our xref for 詮方 is しかた. 
For consistency, and along with the sankoku definition as 仕方がない, I'm going to suggest changing the xref.

The senses in [2] we've marked as "archaic" are also non-archaic senses of 仕方がない, so I wonder...

@@ -28,5 +28,2 @@
-<xref type="see" seq="1982300">どうしようもない</xref>
-<xref type="see" seq="1982300">どうしようもない</xref>
-<xref type="see" seq="1982300">どうしようもない</xref>
-<xref type="see" seq="1982300">どうしようもない</xref>
-<xref type="see" seq="1982300">どうしようもない</xref>
+<xref type="see" seq="1305420">仕方がない・1</xref>
+<xref type="see" seq="1305420">仕方がない・2</xref>

どうしようもない	1572389	42.7%
仕方がない	2110954	57.3%
詮方ない	640	41.6%
詮方無い	54	3.5%
せん方ない	41	2.7%

せん方ない　<- hundreds of book references
為ん方ない <- no ngrams, ~5 book references
為ん方無い <- book references are mostly editions of daijs itself, and other reference books.

https://hinative.com/questions/3589230
「詮方ない」は、古めかしくて固い印象です。若い人が言ったりすると、とても違和感があります。よく使うのは、ドラマや小説で、偉くてある程度歳をとった人が言うセリフです。

そのようなことを議論しても詮方ないであろう。粛々と次の襲撃に備えよ。

1. add surface form
2. mark some [rK] and [sk].
3. mark [rare].  The hinative comment (last reference) is particularly detailed, not sure if that's enough for [form] or anything else though. (dictionary does not mark as such).

Reasonable number of book results.

Was going to change xref as [see=仕方がない[1,2]] because I'm not sure this carries any of the special nuances we've attached specifically to the どうしようもない entry. But I'm not confident, so I'm leaving it and just changing the simple things.

sankoku defn. in its entirety is "仕方がない".  
daijs. mentions どうしようもない.

為ん方無い is the daijs form. Of ~30 google book references, ~25 are dictionaries.  Leaving as [rK] because of daijs.

@@ -13 +13 @@
-<keb>為ん方ない</keb>
+<keb>せん方ない</keb>
@@ -16,0 +17,5 @@
+<ke_inf>&rK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>為ん方ない</keb>
+<ke_inf>&sK;</ke_inf>
@@ -27,0 +33 @@
+<misc>&rare;</misc>

(ngrams)

@@ -5 +5,2 @@
-<keb>為ん方無い</keb>
+<keb>詮方ない</keb>
+<ke_inf>&ateji;</ke_inf>
@@ -9,0 +11,6 @@
+</k_ele>
+<k_ele>
+<keb>為ん方ない</keb>
+</k_ele>
+<k_ele>
+<keb>為ん方無い</keb>