I vote do it, and get a +3 Leather Covered Round Shield. It has 32 armor, so when you put it on your back, projectiles hitting your back see 42 armor+your body armor, so even arbalest bolts do <20 dmg. At this high armor value, it can't be penetrated by bolts (an important consideration for the low-requirement shields).
Even with just 1 skill, it would absorb 5-6 longsword strikes, 3-4 arbalest bolts, etc; durable enough for your intended use.
Think of it this way; if it only absorbs one bolt/arrow every 10 rounds, it has proven more valuable than 1 Ironflesh.