Prism99

If the quilt has to be really packed in to fit, then there can be a risk of insufficient water to dilute any dye bleeds. If you prewashed all of the fabric and know none of it bleeds, then the risk is smaller. (There is still a small risk of "crocking".)

When washing a machine in a top-loader, it's a good idea to not allow the machine to agitate. Stop the machine and hand agitate instead (by pushing down on the quilt). When finished, advance to the spin cycle. Do the same for the rinse cycle. Spin cycles do not damage quilts, but center post agitators are quite hard on them during the agitation cycles.

I would not do a first wash in a domestic front-loader (which is what I have) unless you can adjust it to use lots of water. You typically want lots of water in the first wash to dilute any bleeds sufficiently (and also to soften any glue). I always give my quilts their first wash at the laundromat in the biggest front loading machine they have (a smaller front loader for lap quilts). Front loaders are easier on the quilt, but domestic front loaders usually don't use enough water for that first wash.

It is only rag quilts that some laundromats don't like because of all the lint that is generated. I have never heard of a laundromat rejecting regular quilts.

If the laundromat is far away, do you have a friend or relative nearby with a large capacity washing machine?

Edit: I want to add that you should not use a dryer if you have to really pack the quilt in to get it to fit. I did that once with a mattress cover, and it actually burned sports into the cover from where the cover touched the air holes continuously. The cover was so tightly packed it couldn't change positions within the dryer.