Hi John,
There are examples of how to apply the sound deadening materials on vendor websites and YouTube. As was mentioned by ajmacdon above, you don't have to cover the entire surface to have an significant effect. The better application videos get into that.
Long story short, I put quite a bit of time researching what was available, and especially looking for affordable materials. For sound deadening I found the following product on Amazon and it is a fraction of the cost of DynaMat and similar products:
Noico adhesive butyl/foil deadener ==>
https://www.amazon.com/gp/product/B00UR ... UTF8&psc=1It's made in Russia and is of very good quality. It is quite heavy, as they all are. I have a box here in the garage if you want to come over and see it. There is also a decent video for the product on the Amazon product page.
The other two potential issues are heat transfer from the power train and road, and high heat from the exhaust. I'm using a foil-backed, artificial "jute" material on the inside of the trans tunnel and some parts of the engine compartment. It is light compared the buytl panels and keeps heat out and has some sound deadening properties too. You can see applications of it in my build log. I bought it through an outfit in Bakersfield. It's a very effective and safe material, and pretty inexpensive relative to many other products. I have some samples of that you can look at. You put it on with a spray adhesive.
Neither the butyl panels, nor the foil-backed jute can be used close to high heat sources. I have that situation at the footwells, where the exhaust headers run very close to both of them, and bought what's called 'zero clearance' heat shielding. It can be placed very close to the exhaust, and almost touch it. I found a company in North Carolina that supplies NASCAR teams with one of the most effective, yet (relatively) inexpensive products. I haven't even opened the box yet, because I'm a ways off from applying it. We can open it and look at that too if you like.
Those last two applications may not interest you. However, I wanted a comfortable cruiser, so I don't want hot spots like a lot of Locosts have where you fry your feet or elbows after you've been on the road for a while. I can dig out info on the last 2 product and companies if they interest you.
Cheers,
Lonnie