I gave this advice in a thread yesterday, and give it again...
if your guitarist is soloing a dirt pedal is not going to help the sound spectrum.
You are going to lose the bass that is present during the rest of the song.
Bad idea IMO and IME. I've been there.
When my guitarist is soloing, I think: "yes... room to breath for my regular bass sound".
Then it is not the time for me to pull out distortion... but to let my regular bass sound shine alongside the guitarist's solo. Or I follow him in the solo.
(I don't play doom, but more prog metal.)
Buying a distortion just to fill the gap is a bad idea. It's not your responsibility to become the rhythm guitarist for a few measures.
However, I don't know doom music or doom metal... but I think you could use a fuzz pedal anyway for general purpose.
No... not the BOSS one. I have it and I love it.... but it is very harsh and synthy.
Loses low end and rips your head off. I don't use it much. It's not useful in a band unless you want to sound like a synth or guitar.
Look for something else that is more useful and can add to your role as bassist.
The Wooly Mammoth is cool, but yeah, expensive.
EHX Bass Big Muff would be a good first fuzz.
Or Malekko B:Assmaster is a pearl.
Or what I use often, Big John Hairy Balls.