Sealing around bolt holes

Finally got back to my build after harvest and autumn workload. Have just started to bolt steps etc onto the tender and was wondering what is the best thing to use to seal around the bolt holes to prevent water seeping through. I have isoflexed inside of the tender - should I just bolt everything on and then apply more isoflex inside to cover nuts inside to form a watertight seal?
Thanks for any help.
Simon

Hi ho

Yes that's fine. It will also protect the end of the bolts.

It is better and generally more typical of the real thing to have the nuts on the outside: that way the thread does not corrode and the items can be removed in the future, but obviously Isoflex the internal bolt heads.

Tim