I remember having discussed here, that klingon doesn't possess the grammar to say "if klingon possessed an irrealis suffix, then I wouldn't be writing this post".

So far so good..

I've been trying to find a way to overcome this problem

While Klingon does not possess any formal irrealis grammar like a subjunctive mood, it can still express irrealis nonetheless.

bIje'be'chugh vaj bIHegh
if you do not buy then you will die

Klingon employs no special grammar for the irrealis of you will die, a statement which is not a prediction of definite future events but describes what will happen only if you fail to buy. Even in English no special irrealis is used in the you will die part.

if I possessed foresight, I would have known my dog is stupid

QIp dogwIj 'e' vISov, leSSov vIghajchugh

Without using any special grammar, but employing context, this statement is already an expression of irrealis.

paq'batlh has a couple of examples. Here's one:

jIlay'DI' reH batlh jIpabchugh
   Qapla'meywIj Hoch vIta'ta' 'e' DaHar'a'
Did you think that my word of honor
   Would have carried me this far?

Also note that the word irrealis means anything that states something other than actually is. taHjaj wo' long live the Empire! is an irrealis, for instance, as it is making a wish for something, not stating something that is. -jaj is a suffix which specifically introduces this kind of irrealis. -chugh introduces a conditional irrealis.

So whenever in English you find yourself saying "would have," just use a normal indicative-mood sentence, but give it enough context to make it clear that you are being hypothetical.

Saleghchugh SaQoypa', Sagho', orc mach tlhIH 'e' vIHarmo', 'ej jIQaghpu' pIq 'e' vItu'.

-- 
SuStel
http://trimboli.name