gg5

ムカッパラ and ムカっ腹 can be hidden.

@@ -11 +11 @@
-<keb>ムカっ腹</keb>
+<keb>向かっ腹</keb>
@@ -14 +14,2 @@
-<keb>向かっ腹</keb>
+<keb>ムカっ腹</keb>
+<ke_inf>&sK;</ke_inf>
@@ -25 +26 @@
-<re_nokanji/>
+<re_inf>&sk;</re_inf>
@@ -29 +30 @@
-<s_inf>usu. as 〜が立つ, 〜を立てる</s_inf>
+<s_inf>usu. as 〜が立つ or 〜を立てる</s_inf>
@@ -31,0 +33,2 @@
+<gloss>rage</gloss>
+<gloss>temper</gloss>

GG5 has this. I think it's OK.

wisdom; prog; daijs

むかっ腹　 7,331 58.0%
ムカッ腹　 1,940 15.4%
ムカっ腹　 1,346 10.7% <- adding
向かっ腹　   775  6.1%
向っ腹　　    82  0.6%
むかッ腹　     0  0.0%
むかっぱら   390  3.1%
ムカッパラ   513  4.1% <- adding
ムカっぱら   254  2.0%
ムカッぱら     0  0.0%

Better to gloss it as the full expression?
   "flying into a rage (for no reason); losing one's temper; getting angry"

@@ -8,0 +9,3 @@
+</k_ele>
+<k_ele>
+<keb>ムカっ腹</keb>
@@ -19,0 +23,4 @@
+<r_ele>
+<reb>ムカッパラ</reb>
+<re_nokanji/>
+</r_ele>
@@ -21,0 +29 @@
+<s_inf>usu. as 〜が立つ, 〜を立てる</s_inf>

Google N-gram Corpus Counts
╭─ーーーー─┬───────┬───────╮
│ むかっ腹 │ 7,331 │ 72.4% │
│ ムカッ腹 │ 1,940 │ 19.2% │
│ 向かっ腹 │   775 │  7.7% │
│ 向っ腹　 │    82 │  0.8% │
╰─ーーーー─┴───────┴───────╯

@@ -7,0 +8,3 @@
+<keb>ムカッ腹</keb>
+</k_ele>
+<k_ele>
@@ -11,0 +15 @@
+<ke_inf>&sK;</ke_inf>