Bodywork repair advice?

[KBM]

I have epoxy putty on my car in two places that has dried rock solid, it needs removing and replacing with appropriate sealant as water is getting in through it but no body shop / mechanic wants the the job because of the time outlay involved to remove it. Its on unseen areas, inside car behind tailight and on outside of car behind tailight and slightly under the bumper. I have been told no chemicals can do this do will be chisel and hammer or sand off job which will of course cause some damage to the metal. Can this then be primed with anti rust primer, sprayed and laquered? It does not have to be pretty becasue unseen areas but i want to make sure i will have no corrosion or rust damage in the future? Can see the the yellowy thick hardened putty in images below with locations.

Thanks

 

[Mach1]

I would recommend cleaning up gently and drying the area with an Hair dryer before putting some rubberised underseal paint on the effected areas, I have used this for years and helps to dampen down drumming inside the car and stops the water from creeping into the car through the seams etc.

Hammerite Underbody Seal With Waxoyl Black Car Underseal 500ml | eBay

Apply to the under side of floor pans, inner wheel arches and chassis rails for rust prevention and a smooth finish. Available in a range of sizes and applications. Non drip smooth application gives a great, long lasting finish.

www.ebay.co.uk